| Message ID | 1476505867-24599-2-git-send-email-okaya@codeaurora.org |
|---|---|
| State | Superseded |
| Headers | show |
On Sat, Oct 15, 2016 at 6:31 AM, Sinan Kaya <okaya@codeaurora.org> wrote: > The change introduced in commit 103544d86976 ("ACPI,PCI,IRQ: reduce > resource requirements") removed PCI_USING penalty from > acpi_pci_link_allocate function as there is no longer a fixed size penalty > array for both PCI interrupts greater than 16. > > The array size has been reduced to 16 and array name got prefixed as ISA > since it only is accountable for the ISA interrupts. > > The original change in commit 103544d86976 ("ACPI,PCI,IRQ: reduce > resource requirements") removed penalty assignment in the code for PCI > thinking that we will add the penalty later in acpi_irq_pci_sharing_penalty > function. I'd write the above this way: "Commit 103544d86976 (ACPI,PCI,IRQ: reduce resource requirements) dropped the PCI_USING penalty from acpi_pci_link_allocate() with the assumption that the penalty will be added later in acpi_irq_pci_sharing_penalty()." This conveys essentially the same information (up to some irrelevant bits), but in a clearer way IMO. > > However, this function only gets called if the IRQ number is greater than > 16 and acpi_irq_get_penalty function gets called before ACPI start in > acpi_isa_irq_available and acpi_penalize_isa_irq functions. We can't rely > on iterating the link list. "However, acpi_irq_pci_sharing_penalty() is only called for IRQ numbers above 15. Moreover, acpi_irq_get_penalty() is invoked by acpi_isa_irq_available() and acpi_penalize_isa_irq() before the ACPI initialization and the PCI interrupt links list is not ready at that point, so it cannot be relied on when computing the penalty." > > We need to add the PCI_USING penalty for ISA interrupts too if the link is > in use and matches our ISA IRQ number. "For this reason, the PCI_USING penalty has to be added in acpi_pci_link_allocate() directly if the link has been enabled successfully and the IRQ number is within the ISA range." IIUC > > Signed-off-by: Sinan Kaya <okaya@codeaurora.org> > --- > drivers/acpi/pci_link.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c > index c983bf7..a212709 100644 > --- a/drivers/acpi/pci_link.c > +++ b/drivers/acpi/pci_link.c > @@ -619,6 +619,10 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link) > acpi_device_bid(link->device)); > return -ENODEV; > } else { > + if (link->irq.active < ACPI_MAX_ISA_IRQS) > + acpi_isa_irq_penalty[link->irq.active] += > + PIRQ_PENALTY_PCI_USING; > + There's no need to break the line here and I would put the above after the printk(). Or even after the whole "else" branch (which is unnecessary, but let's limit changes in this patch). > printk(KERN_WARNING PREFIX "%s [%s] enabled at IRQ %d\n", > acpi_device_name(link->device), > acpi_device_bid(link->device), link->irq.active); > -- Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Rafael, On 10/15/2016 8:39 AM, Rafael J. Wysocki wrote: > On Sat, Oct 15, 2016 at 6:31 AM, Sinan Kaya <okaya@codeaurora.org> wrote: >> The change introduced in commit 103544d86976 ("ACPI,PCI,IRQ: reduce >> resource requirements") removed PCI_USING penalty from >> acpi_pci_link_allocate function as there is no longer a fixed size penalty >> array for both PCI interrupts greater than 16. >> >> The array size has been reduced to 16 and array name got prefixed as ISA >> since it only is accountable for the ISA interrupts. >> >> The original change in commit 103544d86976 ("ACPI,PCI,IRQ: reduce >> resource requirements") removed penalty assignment in the code for PCI >> thinking that we will add the penalty later in acpi_irq_pci_sharing_penalty >> function. > > I'd write the above this way: > > "Commit 103544d86976 (ACPI,PCI,IRQ: reduce resource requirements) > dropped the PCI_USING penalty from acpi_pci_link_allocate() with the > assumption that the penalty will be added later in > acpi_irq_pci_sharing_penalty()." > > This conveys essentially the same information (up to some irrelevant > bits), but in a clearer way IMO. > >> >> However, this function only gets called if the IRQ number is greater than >> 16 and acpi_irq_get_penalty function gets called before ACPI start in >> acpi_isa_irq_available and acpi_penalize_isa_irq functions. We can't rely >> on iterating the link list. > > "However, acpi_irq_pci_sharing_penalty() is only called for IRQ > numbers above 15. Moreover, acpi_irq_get_penalty() is invoked by > acpi_isa_irq_available() and acpi_penalize_isa_irq() before the ACPI > initialization and the PCI interrupt links list is not ready at that > point, so it cannot be relied on when computing the penalty." > >> >> We need to add the PCI_USING penalty for ISA interrupts too if the link is >> in use and matches our ISA IRQ number. > > "For this reason, the PCI_USING penalty has to be added in > acpi_pci_link_allocate() directly if the link has been enabled > successfully and the IRQ number is within the ISA range." > > IIUC > >> >> Signed-off-by: Sinan Kaya <okaya@codeaurora.org> >> --- >> drivers/acpi/pci_link.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c >> index c983bf7..a212709 100644 >> --- a/drivers/acpi/pci_link.c >> +++ b/drivers/acpi/pci_link.c >> @@ -619,6 +619,10 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link) >> acpi_device_bid(link->device)); >> return -ENODEV; >> } else { >> + if (link->irq.active < ACPI_MAX_ISA_IRQS) >> + acpi_isa_irq_penalty[link->irq.active] += >> + PIRQ_PENALTY_PCI_USING; >> + > > There's no need to break the line here and I would put the above after > the printk(). > > Or even after the whole "else" branch (which is unnecessary, but let's > limit changes in this patch). > >> printk(KERN_WARNING PREFIX "%s [%s] enabled at IRQ %d\n", >> acpi_device_name(link->device), >> acpi_device_bid(link->device), link->irq.active); >> -- > Thanks for the feedback. I can resubmit with the comments corrected. I'll wait until I hear from Bjorn first. > Thanks, > Rafael >
On Sat, Oct 15, 2016 at 12:31:05AM -0400, Sinan Kaya wrote: > The change introduced in commit 103544d86976 ("ACPI,PCI,IRQ: reduce > resource requirements") removed PCI_USING penalty from > acpi_pci_link_allocate function as there is no longer a fixed size penalty > array for both PCI interrupts greater than 16. > > The array size has been reduced to 16 and array name got prefixed as ISA > since it only is accountable for the ISA interrupts. > > The original change in commit 103544d86976 ("ACPI,PCI,IRQ: reduce > resource requirements") removed penalty assignment in the code for PCI > thinking that we will add the penalty later in acpi_irq_pci_sharing_penalty > function. > > However, this function only gets called if the IRQ number is greater than > 16 and acpi_irq_get_penalty function gets called before ACPI start in > acpi_isa_irq_available and acpi_penalize_isa_irq functions. We can't rely > on iterating the link list. It seems wrong to me that we call acpi_irq_get_penalty() from acpi_irq_penalty_update() and acpi_penalize_isa_irq(). It seems like they should just manipulate acpi_isa_irq_penalty[irq] directly. acpi_irq_penalty_update() is for command-line parameters, so it certainly doesn't need the acpi_irq_pci_sharing_penalty() information (the acpi_link_list should be empty at the time we process the command-line parameters). acpi_penalize_isa_irq() is telling us that a PNP or ACPI device is using the IRQ -- this should modify the IRQ's penalty, but it shouldn't depend on the acpi_irq_pci_sharing_penalty() value at all. > We need to add the PCI_USING penalty for ISA interrupts too if the link is > in use and matches our ISA IRQ number. > > Signed-off-by: Sinan Kaya <okaya@codeaurora.org> > --- > drivers/acpi/pci_link.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c > index c983bf7..a212709 100644 > --- a/drivers/acpi/pci_link.c > +++ b/drivers/acpi/pci_link.c > @@ -619,6 +619,10 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link) > acpi_device_bid(link->device)); > return -ENODEV; > } else { > + if (link->irq.active < ACPI_MAX_ISA_IRQS) > + acpi_isa_irq_penalty[link->irq.active] += > + PIRQ_PENALTY_PCI_USING; > + > printk(KERN_WARNING PREFIX "%s [%s] enabled at IRQ %d\n", > acpi_device_name(link->device), > acpi_device_bid(link->device), link->irq.active); > -- > 1.9.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10/18/2016 6:59 AM, Bjorn Helgaas wrote: >> However, this function only gets called if the IRQ number is greater than >> > 16 and acpi_irq_get_penalty function gets called before ACPI start in >> > acpi_isa_irq_available and acpi_penalize_isa_irq functions. We can't rely >> > on iterating the link list. Maybe, I am missing context here. I can add this paragraph to the commit. When we started cleaning the code we got rid of the acpi_irq_penalty_init function in favor of acpi_irq_pci_sharing_penalty function as it does have some fair amount of code duplication. I tried putting back the acpi_irq_pci_sharing_penalty function into the ISA IRQ path again during the debug and the machine died way too early. We couldn't collect any debug message. This is telling me that we can't even iterate the link list when these two API is called. ISA IRQ need to be handled with special care due to calling order. > It seems wrong to me that we call acpi_irq_get_penalty() from > acpi_irq_penalty_update() and acpi_penalize_isa_irq(). It seems like they > should just manipulate acpi_isa_irq_penalty[irq] directly. > > acpi_irq_penalty_update() is for command-line parameters, so it certainly > doesn't need the acpi_irq_pci_sharing_penalty() information (the > acpi_link_list should be empty at the time we process the command-line > parameters). > > acpi_penalize_isa_irq() is telling us that a PNP or ACPI device is using > the IRQ -- this should modify the IRQ's penalty, but it shouldn't depend on > the acpi_irq_pci_sharing_penalty() value at all. > acpi_irq_get_penalty function knows how to deal with ISA IRQ. So, it is harmless to call it. Also, reading the acpi_isa_irq_penalty array directly isn't also right. It doesn't contain the SCI penalty. So, it returns incorrect penalty value. The rule of thumb is: - all PCI/SCI penalty reads need to go through acpi_isa_irq_penalty function - all ISA penalty writes need to go through acpi_isa_irq_penalty array directly. - we do not support modifying the PCI IRQ penalties greater than the ISA IRQ numbers. The original code supported this.
Sorry, I think I didn't have enough morning coffee. Looking at these again and trying to be specific. On 10/18/2016 8:20 AM, Sinan Kaya wrote: > It seems wrong to me that we call acpi_irq_get_penalty() from >> acpi_irq_penalty_update() and acpi_penalize_isa_irq(). It seems like they >> should just manipulate acpi_isa_irq_penalty[irq] directly. >> >> acpi_irq_penalty_update() is for command-line parameters, so it certainly >> doesn't need the acpi_irq_pci_sharing_penalty() information (the >> acpi_link_list should be empty at the time we process the command-line >> parameters). Calling acpi_irq_get_penalty for ISA IRQ is OK as long as it doesn't have any dynamic IRQ calculation such that acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty. If this is broken, then we need special care so that we don't assign dynamically calcualted sci_penalty back to acpi_isa_irq_penalty[irq]. This results in returning incorrect penalty as acpi_irq_get_penalty = acpi_isa_irq_original_penalty[irq] + 2 * sci_penalty. Now that we added sci_penalty into the acpi_irq_get_penalty function, calling acpi_irq_get_penalty is not correct anymore. This line here needs to be replaced with acpi_isa_irq_penalty[irq] as you suggested. if (used) new_penalty = acpi_irq_get_penalty(irq) + PIRQ_PENALTY_ISA_USED; else new_penalty = 0; acpi_isa_irq_penalty[irq] = new_penalty; >> >> acpi_penalize_isa_irq() is telling us that a PNP or ACPI device is using >> the IRQ -- this should modify the IRQ's penalty, but it shouldn't depend on >> the acpi_irq_pci_sharing_penalty() value at all. >> Same problem here. This line will be broken after the sci_penalty change. acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty(irq) + (active ? PIRQ_PENALTY_ISA_USED : PIRQ_PENALTY_PCI_USING);
Bjorn, On 10/18/2016 6:59 AM, Bjorn Helgaas wrote: > It seems wrong to me that we call acpi_irq_get_penalty() from > acpi_irq_penalty_update() and acpi_penalize_isa_irq(). It seems like they > should just manipulate acpi_isa_irq_penalty[irq] directly. > > acpi_irq_penalty_update() is for command-line parameters, so it certainly > doesn't need the acpi_irq_pci_sharing_penalty() information (the > acpi_link_list should be empty at the time we process the command-line > parameters). > > acpi_penalize_isa_irq() is telling us that a PNP or ACPI device is using > the IRQ -- this should modify the IRQ's penalty, but it shouldn't depend on > the acpi_irq_pci_sharing_penalty() value at all. I posted v4 with this change and also went back to the original implementation for sharing penalty calculation whether the IRQ is ISA or PCI. Let us know what you think. I also realized that calculating sharing penalty while the link object is not initialized is not right. Sinan
On Tue, Oct 18, 2016 at 08:32:44AM -0700, Sinan Kaya wrote: > Sorry, I think I didn't have enough morning coffee. > > Looking at these again and trying to be specific. > > On 10/18/2016 8:20 AM, Sinan Kaya wrote: > > It seems wrong to me that we call acpi_irq_get_penalty() from > >> acpi_irq_penalty_update() and acpi_penalize_isa_irq(). It seems like they > >> should just manipulate acpi_isa_irq_penalty[irq] directly. > >> > >> acpi_irq_penalty_update() is for command-line parameters, so it certainly > >> doesn't need the acpi_irq_pci_sharing_penalty() information (the > >> acpi_link_list should be empty at the time we process the command-line > >> parameters). > > Calling acpi_irq_get_penalty for ISA IRQ is OK as long as it doesn't have > any dynamic IRQ calculation such that acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty. > > If this is broken, then we need special care so that we don't assign > dynamically calcualted sci_penalty back to acpi_isa_irq_penalty[irq]. This > results in returning incorrect penalty as > > acpi_irq_get_penalty = acpi_isa_irq_original_penalty[irq] + 2 * sci_penalty. > > Now that we added sci_penalty into the acpi_irq_get_penalty function, > calling acpi_irq_get_penalty is not correct anymore. This line here needs to > be replaced with acpi_isa_irq_penalty[irq] as you suggested. > > if (used) > new_penalty = acpi_irq_get_penalty(irq) + > PIRQ_PENALTY_ISA_USED; > else > new_penalty = 0; > > acpi_isa_irq_penalty[irq] = new_penalty; > > > >> > >> acpi_penalize_isa_irq() is telling us that a PNP or ACPI device is using > >> the IRQ -- this should modify the IRQ's penalty, but it shouldn't depend on > >> the acpi_irq_pci_sharing_penalty() value at all. > >> > > Same problem here. This line will be broken after the sci_penalty change. > > acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty(irq) + > (active ? PIRQ_PENALTY_ISA_USED : PIRQ_PENALTY_PCI_USING); I think the fragility of this code is an indication that we have a design problem, so I want to step back from the nitty gritty details for a bit and look at the overall design. Let me restate the overall problem: We have a PCI device connected to an interrupt link. The interrupt link can be connected to one of several IRQs, and we want to choose one of those IRQs to minimize IRQ sharing. That means we need information about which IRQs are used. Historically we've started with a compiled-in table of common ISA IRQ usage, and we also collect information about which IRQs are used and which *might* be used. So we have the following inputs: - Compiled-in ISA IRQ usage: the static acpi_isa_irq_penalty[] values. ACPI is *supposed* to tell us about all these usages, so I don't know why we have the table. But it's been there as long as I can remember. The table is probably x86-specific, but we keep it in the supposedly generic pci_link.c. - The "acpi_irq_isa=" and "acpi_irq_pci=" command-line overrides via acpi_irq_pci(). I suppose these are for cases where we can't figure things out automatically. I would resist adding parameters like this today (I would treat the need for them as a bug and look for a fix or a quirk), but we might be stuck with these. - SCI information from the ACPI FADT (acpi_penalize_sci_irq()). - PNPBIOS and PNPACPI device IRQ usage from _CRS and _PRS via acpi_penalize_isa_irq(). This is only for IRQs 0-15, and it does NOT include interrupt link (PNP0C0F) devices because we don't handle them as PNPACPI devices. I think this is related to the fact that PNP0C0F doesn't appear in acpi_pnp_device_ids[]. - For non-PNP0C0F, non-PNPACPI devices, we completely ignore IRQ information from _CRS and _PRS. This seems sub-optimal and possibly buggy. - Interrupt link (PNP0C0F) IRQ usage from _CRS and _PRS via acpi_irq_penalty_init(). This is only for IRQs 0-15, and we only call this on x86. If _PRS exists, we penalize each possible IRQ. If there's no _PRS but _CRS contains an active IRQ, we penalize it. - Interrupt link (PNP0C0F) IRQ usage from _CRS and _PRS when enabling a new link. In acpi_irq_pci_sharing_penalty(), we penalize an IRQ if it appears in _CRS or _PRS of any link device in the system. For IRQs 0-15, this overlaps with the penalization done at boot-time by acpi_irq_penalty_init(): if a device has _PRS, we'll add the "possible" penalty twice (once in acpi_irq_penalty_init() and again in acpi_irq_pci_sharing_penalty()), and the "using" penalty once (in acpi_irq_pci_sharing_penalty()). If a device has no _PRS but has _CRS, the "using" penalty is applied twice (once in once in acpi_irq_penalty_init() and again in acpi_irq_pci_sharing_penalty()) I think this whole thing is baroque and grotesque. Here's a strawman idea: - Maintain a mapping of (IRQ, penalty). Initially all penalties are zero. This is for *all* IRQs, not just ISA ones. This could be a linked list, but the structure is not important as long as we can add things dynamically. - Add a "acpi_penalize_irq()" function similar to acpi_penalize_isa_irq(), but not restricted to ISA, so we can increase the penalty for any IRQ, and maybe we can specify how much penalty to add. - Make acpi_irq_get_penalty() a simple lookup in the mapping. No iterating through all link devices. - If we think the compiled-in penalties are really necessary, move the table to x86 code and add a boot-time loop to use acpi_penalize_irq() to penalize these IRQs. Same for the command-line options. - Change acpi_penalize_sci_irq() to use acpi_penalize_irq(). Probably the mapping needs to pay attention to trigger/polarity somehow, too. - Figure out how to make the ACPI core use acpi_penalize_irq() to based on the _CRS and _PRS of every ACPI device, including PNPACPI, PNP0C0F, etc. Then we can remove acpi_irq_penalty_init(). - Change acpi_pci_link_set() to use acpi_penalize_irq() for the IRQ it is enabling. Conceptually maybe this should be done in the acpi_set_current_resources() path so it happens whenever we use _CRS to enable an IRQ on *any* ACPI device. I think the biggest issue is figuring out how to get the ACPI core to look at the _CRS for *all* devices. If we could do that, I think it could substantially simplify this code. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 20, 2016 at 12:44 AM, Bjorn Helgaas <helgaas@kernel.org> wrote: > On Tue, Oct 18, 2016 at 08:32:44AM -0700, Sinan Kaya wrote: >> Sorry, I think I didn't have enough morning coffee. >> >> Looking at these again and trying to be specific. >> >> On 10/18/2016 8:20 AM, Sinan Kaya wrote: >> > It seems wrong to me that we call acpi_irq_get_penalty() from >> >> acpi_irq_penalty_update() and acpi_penalize_isa_irq(). It seems like they >> >> should just manipulate acpi_isa_irq_penalty[irq] directly. >> >> >> >> acpi_irq_penalty_update() is for command-line parameters, so it certainly >> >> doesn't need the acpi_irq_pci_sharing_penalty() information (the >> >> acpi_link_list should be empty at the time we process the command-line >> >> parameters). >> >> Calling acpi_irq_get_penalty for ISA IRQ is OK as long as it doesn't have >> any dynamic IRQ calculation such that acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty. >> >> If this is broken, then we need special care so that we don't assign >> dynamically calcualted sci_penalty back to acpi_isa_irq_penalty[irq]. This >> results in returning incorrect penalty as >> >> acpi_irq_get_penalty = acpi_isa_irq_original_penalty[irq] + 2 * sci_penalty. >> >> Now that we added sci_penalty into the acpi_irq_get_penalty function, >> calling acpi_irq_get_penalty is not correct anymore. This line here needs to >> be replaced with acpi_isa_irq_penalty[irq] as you suggested. >> >> if (used) >> new_penalty = acpi_irq_get_penalty(irq) + >> PIRQ_PENALTY_ISA_USED; >> else >> new_penalty = 0; >> >> acpi_isa_irq_penalty[irq] = new_penalty; >> >> >> >> >> >> acpi_penalize_isa_irq() is telling us that a PNP or ACPI device is using >> >> the IRQ -- this should modify the IRQ's penalty, but it shouldn't depend on >> >> the acpi_irq_pci_sharing_penalty() value at all. >> >> >> >> Same problem here. This line will be broken after the sci_penalty change. >> >> acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty(irq) + >> (active ? PIRQ_PENALTY_ISA_USED : PIRQ_PENALTY_PCI_USING); > > I think the fragility of this code is an indication that we have a > design problem, so I want to step back from the nitty gritty details > for a bit and look at the overall design. > > Let me restate the overall problem: We have a PCI device connected to > an interrupt link. The interrupt link can be connected to one of > several IRQs, and we want to choose one of those IRQs to minimize IRQ > sharing. > > That means we need information about which IRQs are used. > Historically we've started with a compiled-in table of common ISA IRQ > usage, and we also collect information about which IRQs are used and > which *might* be used. So we have the following inputs: > > - Compiled-in ISA IRQ usage: the static acpi_isa_irq_penalty[] > values. ACPI is *supposed* to tell us about all these usages, so > I don't know why we have the table. But it's been there as long > as I can remember. The table is probably x86-specific, but we > keep it in the supposedly generic pci_link.c. > > - The "acpi_irq_isa=" and "acpi_irq_pci=" command-line overrides via > acpi_irq_pci(). I suppose these are for cases where we can't > figure things out automatically. I would resist adding parameters > like this today (I would treat the need for them as a bug and look > for a fix or a quirk), but we might be stuck with these. > > - SCI information from the ACPI FADT (acpi_penalize_sci_irq()). > > - PNPBIOS and PNPACPI device IRQ usage from _CRS and _PRS via > acpi_penalize_isa_irq(). This is only for IRQs 0-15, and it does > NOT include interrupt link (PNP0C0F) devices because we don't > handle them as PNPACPI devices. I think this is related to the > fact that PNP0C0F doesn't appear in acpi_pnp_device_ids[]. > > - For non-PNP0C0F, non-PNPACPI devices, we completely ignore IRQ > information from _CRS and _PRS. This seems sub-optimal and > possibly buggy. > > - Interrupt link (PNP0C0F) IRQ usage from _CRS and _PRS via > acpi_irq_penalty_init(). This is only for IRQs 0-15, and we only > call this on x86. If _PRS exists, we penalize each possible IRQ. > If there's no _PRS but _CRS contains an active IRQ, we penalize > it. > > - Interrupt link (PNP0C0F) IRQ usage from _CRS and _PRS when > enabling a new link. In acpi_irq_pci_sharing_penalty(), we > penalize an IRQ if it appears in _CRS or _PRS of any link device > in the system. > > For IRQs 0-15, this overlaps with the penalization done at > boot-time by acpi_irq_penalty_init(): if a device has _PRS, we'll > add the "possible" penalty twice (once in acpi_irq_penalty_init() > and again in acpi_irq_pci_sharing_penalty()), and the "using" > penalty once (in acpi_irq_pci_sharing_penalty()). > > If a device has no _PRS but has _CRS, the "using" penalty is > applied twice (once in once in acpi_irq_penalty_init() and again > in acpi_irq_pci_sharing_penalty()) > > I think this whole thing is baroque and grotesque. While I agree, I also would like the regression introduced here to be fixed ASAP. So do you want me to revert all of the changes made here so far and start over? Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10/19/2016 3:44 PM, Bjorn Helgaas wrote: [cut] >> >> Same problem here. This line will be broken after the sci_penalty change. >> >> acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty(irq) + >> (active ? PIRQ_PENALTY_ISA_USED : PIRQ_PENALTY_PCI_USING); > > I think the fragility of this code is an indication that we have a > design problem, so I want to step back from the nitty gritty details > for a bit and look at the overall design. This is all because we started with a very simple design where we replaced the array with a get_penalty function. Set penalty function would dynamically reallocate the link list so that we have a design that works no matter what the number of IRQs are. As we hit the first problem on existing platform, we realized that we can't actually dynamically reallocate an interrupt because get_penalty function gets called from early boot stages where heap is not initialized yet. Then, we started restructuring the code so that we can discover the IRQs by iterating the link list rather than using an array. While transitioning into this new design, we forgot the fact that irq_get_penalty function became a fixed array penalty + dynamically calculated penalty. This line was trying to increment the static array but ended up gathering the dynamic pieces together. This obviously is a bug and was forgotten in the code. > > Let me restate the overall problem: We have a PCI device connected to > an interrupt link. The interrupt link can be connected to one of > several IRQs, and we want to choose one of those IRQs to minimize IRQ > sharing. > > That means we need information about which IRQs are used. > Historically we've started with a compiled-in table of common ISA IRQ > usage, and we also collect information about which IRQs are used and > which *might* be used. So we have the following inputs: > > - Compiled-in ISA IRQ usage: the static acpi_isa_irq_penalty[] > values. ACPI is *supposed* to tell us about all these usages, so > I don't know why we have the table. But it's been there as long > as I can remember. The table is probably x86-specific, but we > keep it in the supposedly generic pci_link.c. > I think it is because the ISA IRQ functions get called in early boot stages and there is no heap allocator at that point of execution. > - The "acpi_irq_isa=" and "acpi_irq_pci=" command-line overrides via > acpi_irq_pci(). I suppose these are for cases where we can't > figure things out automatically. I would resist adding parameters > like this today (I would treat the need for them as a bug and look > for a fix or a quirk), but we might be stuck with these. > > - SCI information from the ACPI FADT (acpi_penalize_sci_irq()). > > - PNPBIOS and PNPACPI device IRQ usage from _CRS and _PRS via > acpi_penalize_isa_irq(). This is only for IRQs 0-15, and it does > NOT include interrupt link (PNP0C0F) devices because we don't > handle them as PNPACPI devices. I think this is related to the > fact that PNP0C0F doesn't appear in acpi_pnp_device_ids[]. The original code supports the entire IRQ range (0..255). We limited it to 16 during redesign. > > - For non-PNP0C0F, non-PNPACPI devices, we completely ignore IRQ > information from _CRS and _PRS. This seems sub-optimal and > possibly buggy. > > - Interrupt link (PNP0C0F) IRQ usage from _CRS and _PRS via > acpi_irq_penalty_init(). This is only for IRQs 0-15, and we only > call this on x86. If _PRS exists, we penalize each possible IRQ. > If there's no _PRS but _CRS contains an active IRQ, we penalize > it. Correct. > > - Interrupt link (PNP0C0F) IRQ usage from _CRS and _PRS when > enabling a new link. In acpi_irq_pci_sharing_penalty(), we > penalize an IRQ if it appears in _CRS or _PRS of any link device > in the system. > > For IRQs 0-15, this overlaps with the penalization done at > boot-time by acpi_irq_penalty_init(): if a device has _PRS, we'll > add the "possible" penalty twice (once in acpi_irq_penalty_init() > and again in acpi_irq_pci_sharing_penalty()), and the "using" > penalty once (in acpi_irq_pci_sharing_penalty()). > > If a device has no _PRS but has _CRS, the "using" penalty is > applied twice (once in once in acpi_irq_penalty_init() and again > in acpi_irq_pci_sharing_penalty()) > > I think this whole thing is baroque and grotesque. Regardless of these, we hit four different bugs because we didn't understand the usage model. 1. You can't use kmalloc in IRQ get penalty 2. SCI IRQ type cannot be gathered from IRQ API 3. acpi_irq_penalty cannot be called from early stages since it is iterating the link list. If there is a penalty assignment requirement from early stages, this needs to be done on a statically allocated array. 4. acpi_irq_penalty_init is redundant. > > Here's a strawman idea: > > - Maintain a mapping of (IRQ, penalty). Initially all penalties are > zero. This is for *all* IRQs, not just ISA ones. This could be a > linked list, but the structure is not important as long as we can > add things dynamically. Dynamic allocation doesn't work due to early calls from x86 architecture. This is the reason why we iterate the link objects. > > - Add a "acpi_penalize_irq()" function similar to > acpi_penalize_isa_irq(), but not restricted to ISA, so we can > increase the penalty for any IRQ, and maybe we can specify how > much penalty to add. This was my first patch. It didn't work due to heap requirements. > > - Make acpi_irq_get_penalty() a simple lookup in the mapping. No > iterating through all link devices. > > - If we think the compiled-in penalties are really necessary, move > the table to x86 code and add a boot-time loop to use > acpi_penalize_irq() to penalize these IRQs. Same for the > command-line options. I agree, we can move all of the ISA interrupt stuff out of this file if we want to. I really don't like the fact that we have a acpi_penalize_isa_irq function. The penalty information should have been contained in this file. acpi_penalize_isa_irq gets called from arbitrary contexts. I'm not sure adding a acpi_penalize_irq function is a good idea. All penalty users should have been in this file. > > - Change acpi_penalize_sci_irq() to use acpi_penalize_irq(). > Probably the mapping needs to pay attention to trigger/polarity > somehow, too. > > - Figure out how to make the ACPI core use acpi_penalize_irq() to > based on the _CRS and _PRS of every ACPI device, including > PNPACPI, PNP0C0F, etc. Then we can remove acpi_irq_penalty_init(). > I think this is a new feature. > - Change acpi_pci_link_set() to use acpi_penalize_irq() for the IRQ > it is enabling. Conceptually maybe this should be done in the > acpi_set_current_resources() path so it happens whenever we use > _CRS to enable an IRQ on *any* ACPI device. > > I think the biggest issue is figuring out how to get the ACPI core to > look at the _CRS for *all* devices. If we could do that, I think it > could substantially simplify this code. I think my V4 patch satisfies all of these requirements and also fixes the existing regression. (I have test vectors captured from the machines with issues.) 1. You can't use kmalloc in IRQ get penalty 2. SCI IRQ type cannot be gathered from IRQ API 3. acpi_irq_penalty cannot be called from early stages since it is iterating the link list. If there is a penalty assignment requirement from early stages, this needs to be done on a statically allocated array. 4. acpi_irq_penalty_init is redundant. and your goal to have some common code that can be used with any IRQ we want. If we want to move the ISA pieces out of this file, that can be done too. We can also add support for PNPACPI. I'm not a very big fan of scratch everything and start from beginning approach. This refactoring effort already failed 3 times. I'd like to close the issue and move on. > > Bjorn > -- > To unsubscribe from this list: send the line "unsubscribe linux-pci" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
On Thu, Oct 20, 2016 at 10:01 PM, Sinan Kaya <okaya@codeaurora.org> wrote: > On 10/19/2016 3:44 PM, Bjorn Helgaas wrote: [cut] > If we want to move the ISA pieces out of this file, that can be done too. > We can also add support for PNPACPI. I'm not a very big fan of scratch > everything and start from beginning approach. This refactoring effort already > failed 3 times. I'd like to close the issue and move on. Understood, but we have broken this for too many times already. Either we have a minimum fix that is known working or we are going back. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10/20/2016 2:08 PM, Rafael J. Wysocki wrote: > On Thu, Oct 20, 2016 at 10:01 PM, Sinan Kaya <okaya@codeaurora.org> wrote: >> On 10/19/2016 3:44 PM, Bjorn Helgaas wrote: > > [cut] > >> If we want to move the ISA pieces out of this file, that can be done too. >> We can also add support for PNPACPI. I'm not a very big fan of scratch >> everything and start from beginning approach. This refactoring effort already >> failed 3 times. I'd like to close the issue and move on. > > Understood, but we have broken this for too many times already. > > Either we have a minimum fix that is known working or we are going back. Agreed. I think my V4 patch satisfies our short term goals and fixes the issue you are seeing. IMO, it is good enough for the moment. > > Thanks, > Rafael >
On Thu, Oct 20, 2016 at 01:17:23AM +0200, Rafael J. Wysocki wrote: > On Thu, Oct 20, 2016 at 12:44 AM, Bjorn Helgaas <helgaas@kernel.org> wrote: > > On Tue, Oct 18, 2016 at 08:32:44AM -0700, Sinan Kaya wrote: > >> Sorry, I think I didn't have enough morning coffee. > >> > >> Looking at these again and trying to be specific. > >> > >> On 10/18/2016 8:20 AM, Sinan Kaya wrote: > >> > It seems wrong to me that we call acpi_irq_get_penalty() from > >> >> acpi_irq_penalty_update() and acpi_penalize_isa_irq(). It seems like they > >> >> should just manipulate acpi_isa_irq_penalty[irq] directly. > >> >> > >> >> acpi_irq_penalty_update() is for command-line parameters, so it certainly > >> >> doesn't need the acpi_irq_pci_sharing_penalty() information (the > >> >> acpi_link_list should be empty at the time we process the command-line > >> >> parameters). > >> > >> Calling acpi_irq_get_penalty for ISA IRQ is OK as long as it doesn't have > >> any dynamic IRQ calculation such that acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty. > >> > >> If this is broken, then we need special care so that we don't assign > >> dynamically calcualted sci_penalty back to acpi_isa_irq_penalty[irq]. This > >> results in returning incorrect penalty as > >> > >> acpi_irq_get_penalty = acpi_isa_irq_original_penalty[irq] + 2 * sci_penalty. > >> > >> Now that we added sci_penalty into the acpi_irq_get_penalty function, > >> calling acpi_irq_get_penalty is not correct anymore. This line here needs to > >> be replaced with acpi_isa_irq_penalty[irq] as you suggested. > >> > >> if (used) > >> new_penalty = acpi_irq_get_penalty(irq) + > >> PIRQ_PENALTY_ISA_USED; > >> else > >> new_penalty = 0; > >> > >> acpi_isa_irq_penalty[irq] = new_penalty; > >> > >> > >> >> > >> >> acpi_penalize_isa_irq() is telling us that a PNP or ACPI device is using > >> >> the IRQ -- this should modify the IRQ's penalty, but it shouldn't depend on > >> >> the acpi_irq_pci_sharing_penalty() value at all. > >> >> > >> > >> Same problem here. This line will be broken after the sci_penalty change. > >> > >> acpi_isa_irq_penalty[irq] = acpi_irq_get_penalty(irq) + > >> (active ? PIRQ_PENALTY_ISA_USED : PIRQ_PENALTY_PCI_USING); > > > > I think the fragility of this code is an indication that we have a > > design problem, so I want to step back from the nitty gritty details > > for a bit and look at the overall design. > > > > Let me restate the overall problem: We have a PCI device connected to > > an interrupt link. The interrupt link can be connected to one of > > several IRQs, and we want to choose one of those IRQs to minimize IRQ > > sharing. > > > > That means we need information about which IRQs are used. > > Historically we've started with a compiled-in table of common ISA IRQ > > usage, and we also collect information about which IRQs are used and > > which *might* be used. So we have the following inputs: > > > > - Compiled-in ISA IRQ usage: the static acpi_isa_irq_penalty[] > > values. ACPI is *supposed* to tell us about all these usages, so > > I don't know why we have the table. But it's been there as long > > as I can remember. The table is probably x86-specific, but we > > keep it in the supposedly generic pci_link.c. > > > > - The "acpi_irq_isa=" and "acpi_irq_pci=" command-line overrides via > > acpi_irq_pci(). I suppose these are for cases where we can't > > figure things out automatically. I would resist adding parameters > > like this today (I would treat the need for them as a bug and look > > for a fix or a quirk), but we might be stuck with these. > > > > - SCI information from the ACPI FADT (acpi_penalize_sci_irq()). > > > > - PNPBIOS and PNPACPI device IRQ usage from _CRS and _PRS via > > acpi_penalize_isa_irq(). This is only for IRQs 0-15, and it does > > NOT include interrupt link (PNP0C0F) devices because we don't > > handle them as PNPACPI devices. I think this is related to the > > fact that PNP0C0F doesn't appear in acpi_pnp_device_ids[]. > > > > - For non-PNP0C0F, non-PNPACPI devices, we completely ignore IRQ > > information from _CRS and _PRS. This seems sub-optimal and > > possibly buggy. > > > > - Interrupt link (PNP0C0F) IRQ usage from _CRS and _PRS via > > acpi_irq_penalty_init(). This is only for IRQs 0-15, and we only > > call this on x86. If _PRS exists, we penalize each possible IRQ. > > If there's no _PRS but _CRS contains an active IRQ, we penalize > > it. > > > > - Interrupt link (PNP0C0F) IRQ usage from _CRS and _PRS when > > enabling a new link. In acpi_irq_pci_sharing_penalty(), we > > penalize an IRQ if it appears in _CRS or _PRS of any link device > > in the system. > > > > For IRQs 0-15, this overlaps with the penalization done at > > boot-time by acpi_irq_penalty_init(): if a device has _PRS, we'll > > add the "possible" penalty twice (once in acpi_irq_penalty_init() > > and again in acpi_irq_pci_sharing_penalty()), and the "using" > > penalty once (in acpi_irq_pci_sharing_penalty()). > > > > If a device has no _PRS but has _CRS, the "using" penalty is > > applied twice (once in once in acpi_irq_penalty_init() and again > > in acpi_irq_pci_sharing_penalty()) > > > > I think this whole thing is baroque and grotesque. > > While I agree, I also would like the regression introduced here to be > fixed ASAP. > > So do you want me to revert all of the changes made here so far and start over? You're right, of course. We need to fix the regression first, then worry about longer-term changes. I don't think we necessarily need to fix *all* the issues with the current scheme, because most of them have been there forever and I don't think people are tripping over them. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Oct 20, 2016 at 01:01:04PM -0700, Sinan Kaya wrote: > On 10/19/2016 3:44 PM, Bjorn Helgaas wrote: > > - Maintain a mapping of (IRQ, penalty). Initially all penalties are > > zero. This is for *all* IRQs, not just ISA ones. This could be a > > linked list, but the structure is not important as long as we can > > add things dynamically. > > Dynamic allocation doesn't work due to early calls from x86 architecture. > This is the reason why we iterate the link objects. Where exactly is this early penalization? That seems to be the biggest problem. Well, maybe the question of ACPI core parsing of _CRS/_PRS is a bigger structural problem, but the dynamic allocation thing at least seems solvable. -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10/20/2016 7:41 PM, Bjorn Helgaas wrote: > On Thu, Oct 20, 2016 at 01:01:04PM -0700, Sinan Kaya wrote: >> On 10/19/2016 3:44 PM, Bjorn Helgaas wrote: > >>> - Maintain a mapping of (IRQ, penalty). Initially all penalties are >>> zero. This is for *all* IRQs, not just ISA ones. This could be a >>> linked list, but the structure is not important as long as we can >>> add things dynamically. >> >> Dynamic allocation doesn't work due to early calls from x86 architecture. >> This is the reason why we iterate the link objects. > > Where exactly is this early penalization? That seems to be the > biggest problem. Well, maybe the question of ACPI core parsing of > _CRS/_PRS is a bigger structural problem, but the dynamic allocation > thing at least seems solvable. > http://marc.info/?l=linux-acpi&m=145580159209240&w=2
On Sat, Oct 15, 2016 at 12:31:05AM -0400, Sinan Kaya wrote: > The change introduced in commit 103544d86976 ("ACPI,PCI,IRQ: reduce > resource requirements") removed PCI_USING penalty from > acpi_pci_link_allocate function as there is no longer a fixed size penalty > array for both PCI interrupts greater than 16. > > The array size has been reduced to 16 and array name got prefixed as ISA > since it only is accountable for the ISA interrupts. > > The original change in commit 103544d86976 ("ACPI,PCI,IRQ: reduce > resource requirements") removed penalty assignment in the code for PCI > thinking that we will add the penalty later in acpi_irq_pci_sharing_penalty > function. > > However, this function only gets called if the IRQ number is greater than > 16 and acpi_irq_get_penalty function gets called before ACPI start in > acpi_isa_irq_available and acpi_penalize_isa_irq functions. We can't rely > on iterating the link list. > > We need to add the PCI_USING penalty for ISA interrupts too if the link is > in use and matches our ISA IRQ number. I think the history about the array size is more than is necessary for this changelog. I think the useful part is something like this: ACPI: pci_link: Include PIRQ_PENALTY_PCI_USING for ISA IRQs 103544d86976 ("ACPI,PCI,IRQ: reduce resource requirements") replaced the addition of PIRQ_PENALTY_PCI_USING in acpi_pci_link_allocate() with an addition in acpi_irq_pci_sharing_penalty(), but f7eca374f000 ("ACPI,PCI,IRQ: separate ISA penalty calculation") removed the use of acpi_irq_pci_sharing_penalty() for ISA IRQs. Therefore, PIRQ_PENALTY_PCI_USING is missing from ISA IRQs used by interrupt links. Include that penalty by adding it in the acpi_pci_link_allocate() path. Fixes: f7eca374f000 ("ACPI,PCI,IRQ: separate ISA penalty calculation") > Signed-off-by: Sinan Kaya <okaya@codeaurora.org> Acked-by: Bjorn Helgaas <bhelgaas@google.com> > --- > drivers/acpi/pci_link.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c > index c983bf7..a212709 100644 > --- a/drivers/acpi/pci_link.c > +++ b/drivers/acpi/pci_link.c > @@ -619,6 +619,10 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link) > acpi_device_bid(link->device)); > return -ENODEV; > } else { > + if (link->irq.active < ACPI_MAX_ISA_IRQS) > + acpi_isa_irq_penalty[link->irq.active] += > + PIRQ_PENALTY_PCI_USING; > + > printk(KERN_WARNING PREFIX "%s [%s] enabled at IRQ %d\n", > acpi_device_name(link->device), > acpi_device_bid(link->device), link->irq.active); > -- > 1.9.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 10/22/2016 7:58 PM, Bjorn Helgaas wrote: > On Sat, Oct 15, 2016 at 12:31:05AM -0400, Sinan Kaya wrote: >> The change introduced in commit 103544d86976 ("ACPI,PCI,IRQ: reduce >> resource requirements") removed PCI_USING penalty from >> acpi_pci_link_allocate function as there is no longer a fixed size penalty >> array for both PCI interrupts greater than 16. >> >> The array size has been reduced to 16 and array name got prefixed as ISA >> since it only is accountable for the ISA interrupts. >> >> The original change in commit 103544d86976 ("ACPI,PCI,IRQ: reduce >> resource requirements") removed penalty assignment in the code for PCI >> thinking that we will add the penalty later in acpi_irq_pci_sharing_penalty >> function. >> >> However, this function only gets called if the IRQ number is greater than >> 16 and acpi_irq_get_penalty function gets called before ACPI start in >> acpi_isa_irq_available and acpi_penalize_isa_irq functions. We can't rely >> on iterating the link list. >> >> We need to add the PCI_USING penalty for ISA interrupts too if the link is >> in use and matches our ISA IRQ number. > > I think the history about the array size is more than is necessary for this > changelog. I think the useful part is something like this: > > ACPI: pci_link: Include PIRQ_PENALTY_PCI_USING for ISA IRQs > > 103544d86976 ("ACPI,PCI,IRQ: reduce resource requirements") replaced > the addition of PIRQ_PENALTY_PCI_USING in acpi_pci_link_allocate() > with an addition in acpi_irq_pci_sharing_penalty(), but f7eca374f000 > ("ACPI,PCI,IRQ: separate ISA penalty calculation") removed the use > of acpi_irq_pci_sharing_penalty() for ISA IRQs. > > Therefore, PIRQ_PENALTY_PCI_USING is missing from ISA IRQs used by > interrupt links. Include that penalty by adding it in the > acpi_pci_link_allocate() path. > > Fixes: f7eca374f000 ("ACPI,PCI,IRQ: separate ISA penalty calculation") > >> Signed-off-by: Sinan Kaya <okaya@codeaurora.org> > > Acked-by: Bjorn Helgaas <bhelgaas@google.com> OK. Updated as suggested. > >> --- >> drivers/acpi/pci_link.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c >> index c983bf7..a212709 100644 >> --- a/drivers/acpi/pci_link.c >> +++ b/drivers/acpi/pci_link.c >> @@ -619,6 +619,10 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link) >> acpi_device_bid(link->device)); >> return -ENODEV; >> } else { >> + if (link->irq.active < ACPI_MAX_ISA_IRQS) >> + acpi_isa_irq_penalty[link->irq.active] += >> + PIRQ_PENALTY_PCI_USING; >> + >> printk(KERN_WARNING PREFIX "%s [%s] enabled at IRQ %d\n", >> acpi_device_name(link->device), >> acpi_device_bid(link->device), link->irq.active); >> -- >> 1.9.1 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >
diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c index c983bf7..a212709 100644 --- a/drivers/acpi/pci_link.c +++ b/drivers/acpi/pci_link.c @@ -619,6 +619,10 @@ static int acpi_pci_link_allocate(struct acpi_pci_link *link) acpi_device_bid(link->device)); return -ENODEV; } else { + if (link->irq.active < ACPI_MAX_ISA_IRQS) + acpi_isa_irq_penalty[link->irq.active] += + PIRQ_PENALTY_PCI_USING; + printk(KERN_WARNING PREFIX "%s [%s] enabled at IRQ %d\n", acpi_device_name(link->device), acpi_device_bid(link->device), link->irq.active);
The change introduced in commit 103544d86976 ("ACPI,PCI,IRQ: reduce resource requirements") removed PCI_USING penalty from acpi_pci_link_allocate function as there is no longer a fixed size penalty array for both PCI interrupts greater than 16. The array size has been reduced to 16 and array name got prefixed as ISA since it only is accountable for the ISA interrupts. The original change in commit 103544d86976 ("ACPI,PCI,IRQ: reduce resource requirements") removed penalty assignment in the code for PCI thinking that we will add the penalty later in acpi_irq_pci_sharing_penalty function. However, this function only gets called if the IRQ number is greater than 16 and acpi_irq_get_penalty function gets called before ACPI start in acpi_isa_irq_available and acpi_penalize_isa_irq functions. We can't rely on iterating the link list. We need to add the PCI_USING penalty for ISA interrupts too if the link is in use and matches our ISA IRQ number. Signed-off-by: Sinan Kaya <okaya@codeaurora.org> --- drivers/acpi/pci_link.c | 4 ++++ 1 file changed, 4 insertions(+)