| Message ID | 20201215024542.18888-3-zev@bewilderbeest.net |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | aspeed-video: extend spurious interrupt handling | expand |
On Tue, 15 Dec 2020 at 02:46, Zev Weiss <zev@bewilderbeest.net> wrote: > > Instead of testing and conditionally clearing them one by one, we can > instead just unconditionally clear them all at once. > > Signed-off-by: Zev Weiss <zev@bewilderbeest.net> I had a poke at the assembly and it looks like GCC is clearing the bits unconditionally anyway, so removing the tests provides no change. Combining them is a good further optimization. Reviewed-by: Joel Stanley <joel@jms.id.au> A question unrelated to this patch: Do you know why the driver doesn't clear the status bits in the interrupt handler? I would expect it to write the value of sts back to the register to ack the pending interrupt. > --- > drivers/media/platform/aspeed-video.c | 19 ++++++++++--------- > 1 file changed, 10 insertions(+), 9 deletions(-) > > diff --git a/drivers/media/platform/aspeed-video.c b/drivers/media/platform/aspeed-video.c > index eb02043532e3..218aae3be809 100644 > --- a/drivers/media/platform/aspeed-video.c > +++ b/drivers/media/platform/aspeed-video.c > @@ -558,6 +558,14 @@ static void aspeed_video_irq_res_change(struct aspeed_video *video, ulong delay) > schedule_delayed_work(&video->res_work, delay); > } > > +/* > + * Interrupts that we don't use but have to explicitly ignore because the > + * hardware asserts them even when they're disabled in the VE_INTERRUPT_CTRL > + * register. > + */ > +#define VE_SPURIOUS_IRQS \ > + (VE_INTERRUPT_CAPTURE_COMPLETE | VE_INTERRUPT_FRAME_COMPLETE) > + > static irqreturn_t aspeed_video_irq(int irq, void *arg) > { > struct aspeed_video *video = arg; > @@ -630,15 +638,8 @@ static irqreturn_t aspeed_video_irq(int irq, void *arg) > aspeed_video_start_frame(video); > } > > - /* > - * CAPTURE_COMPLETE and FRAME_COMPLETE interrupts come even when these > - * are disabled in the VE_INTERRUPT_CTRL register so clear them to > - * prevent unnecessary interrupt calls. > - */ > - if (sts & VE_INTERRUPT_CAPTURE_COMPLETE) > - sts &= ~VE_INTERRUPT_CAPTURE_COMPLETE; > - if (sts & VE_INTERRUPT_FRAME_COMPLETE) > - sts &= ~VE_INTERRUPT_FRAME_COMPLETE; > + /* Squash known bogus interrupts */ > + sts &= ~VE_SPURIOUS_IRQS; > > if (sts) > dev_err_ratelimited(video->dev, "unexpected interrupt asserted:" > -- > 2.29.2 >
On Mon, Dec 21, 2020 at 10:47:37PM CST, Joel Stanley wrote: >On Tue, 15 Dec 2020 at 02:46, Zev Weiss <zev@bewilderbeest.net> wrote: >> >> Instead of testing and conditionally clearing them one by one, we can >> instead just unconditionally clear them all at once. >> >> Signed-off-by: Zev Weiss <zev@bewilderbeest.net> > >I had a poke at the assembly and it looks like GCC is clearing the >bits unconditionally anyway, so removing the tests provides no change. > >Combining them is a good further optimization. > >Reviewed-by: Joel Stanley <joel@jms.id.au> > >A question unrelated to this patch: Do you know why the driver doesn't >clear the status bits in the interrupt handler? I would expect it to >write the value of sts back to the register to ack the pending >interrupt. > No, I don't, and I was sort of wondering the same thing actually -- I'm not deeply familiar with this hardware or driver though, so I was a bit hesitant to start messing with things. (Though maybe doing so would address the "stickiness" aspect when it does manifest.) Perhaps Eddie or Jae can shed some light here? Zev
On Tue, 22 Dec 2020 at 19:14, Zev Weiss <zev@bewilderbeest.net> wrote: > > On Mon, Dec 21, 2020 at 10:47:37PM CST, Joel Stanley wrote: > >On Tue, 15 Dec 2020 at 02:46, Zev Weiss <zev@bewilderbeest.net> wrote: > >> > >> Instead of testing and conditionally clearing them one by one, we can > >> instead just unconditionally clear them all at once. > >> > >> Signed-off-by: Zev Weiss <zev@bewilderbeest.net> > > > >I had a poke at the assembly and it looks like GCC is clearing the > >bits unconditionally anyway, so removing the tests provides no change. > > > >Combining them is a good further optimization. > > > >Reviewed-by: Joel Stanley <joel@jms.id.au> > > > >A question unrelated to this patch: Do you know why the driver doesn't > >clear the status bits in the interrupt handler? I would expect it to > >write the value of sts back to the register to ack the pending > >interrupt. > > > > No, I don't, and I was sort of wondering the same thing actually -- I'm > not deeply familiar with this hardware or driver though, so I was a bit > hesitant to start messing with things. (Though maybe doing so would > address the "stickiness" aspect when it does manifest.) Perhaps Eddie > or Jae can shed some light here? I think you're onto something here - this would be why the status bits seem to stick until the device is reset. Until Aspeed can clarify if this is a hardware or software issue, I suggest we ack the bits and log a message when we see them, instead of always ignoring them without taking any action. Can you write a patch that changes the interrupt handler to ack status bits as it handles each of them? > > > Zev >
> -----Original Message----- > From: Joel Stanley <joel@jms.id.au> > Sent: Wednesday, December 23, 2020 9:07 AM > To: Zev Weiss <zev@bewilderbeest.net>; Ryan Chen > <ryan_chen@aspeedtech.com> > Cc: Eddie James <eajames@linux.ibm.com>; Mauro Carvalho Chehab > <mchehab@kernel.org>; Andrew Jeffery <andrew@aj.id.au>; > linux-media@vger.kernel.org; OpenBMC Maillist <openbmc@lists.ozlabs.org>; > Linux ARM <linux-arm-kernel@lists.infradead.org>; linux-aspeed > <linux-aspeed@lists.ozlabs.org>; Linux Kernel Mailing List > <linux-kernel@vger.kernel.org>; Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> > Subject: Re: [PATCH 2/3] aspeed-video: clear spurious interrupt bits > unconditionally > > On Tue, 22 Dec 2020 at 19:14, Zev Weiss <zev@bewilderbeest.net> wrote: > > > > On Mon, Dec 21, 2020 at 10:47:37PM CST, Joel Stanley wrote: > > >On Tue, 15 Dec 2020 at 02:46, Zev Weiss <zev@bewilderbeest.net> wrote: > > >> > > >> Instead of testing and conditionally clearing them one by one, we > > >> can instead just unconditionally clear them all at once. > > >> > > >> Signed-off-by: Zev Weiss <zev@bewilderbeest.net> > > > > > >I had a poke at the assembly and it looks like GCC is clearing the > > >bits unconditionally anyway, so removing the tests provides no change. > > > > > >Combining them is a good further optimization. > > > > > >Reviewed-by: Joel Stanley <joel@jms.id.au> > > > > > >A question unrelated to this patch: Do you know why the driver > > >doesn't clear the status bits in the interrupt handler? I would > > >expect it to write the value of sts back to the register to ack the > > >pending interrupt. > > > > > > > No, I don't, and I was sort of wondering the same thing actually -- > > I'm not deeply familiar with this hardware or driver though, so I was > > a bit hesitant to start messing with things. (Though maybe doing so > > would address the "stickiness" aspect when it does manifest.) Perhaps > > Eddie or Jae can shed some light here? > > I think you're onto something here - this would be why the status bits seem to > stick until the device is reset. > > Until Aspeed can clarify if this is a hardware or software issue, I suggest we ack > the bits and log a message when we see them, instead of always ignoring them > without taking any action. > > Can you write a patch that changes the interrupt handler to ack status bits as it > handles each of them? > Hello Zev, before the patch, do you met issue with irq handler? [continuous incoming?] In aspeed_video_irq handler should only handle enable interrupt expected. u32 sts = aspeed_video_read(video, VE_INTERRUPT_STATUS); + sts &= aspeed_video_read(video, VE_INTERRUPT_CTRL); Ryan > > > > > > Zev > >
On Tue, Dec 22, 2020 at 08:53:33PM CST, Ryan Chen wrote: >> -----Original Message----- >> From: Joel Stanley <joel@jms.id.au> >> Sent: Wednesday, December 23, 2020 9:07 AM >> To: Zev Weiss <zev@bewilderbeest.net>; Ryan Chen >> <ryan_chen@aspeedtech.com> >> Cc: Eddie James <eajames@linux.ibm.com>; Mauro Carvalho Chehab >> <mchehab@kernel.org>; Andrew Jeffery <andrew@aj.id.au>; >> linux-media@vger.kernel.org; OpenBMC Maillist <openbmc@lists.ozlabs.org>; >> Linux ARM <linux-arm-kernel@lists.infradead.org>; linux-aspeed >> <linux-aspeed@lists.ozlabs.org>; Linux Kernel Mailing List >> <linux-kernel@vger.kernel.org>; Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> >> Subject: Re: [PATCH 2/3] aspeed-video: clear spurious interrupt bits >> unconditionally >> >> On Tue, 22 Dec 2020 at 19:14, Zev Weiss <zev@bewilderbeest.net> wrote: >> > >> > On Mon, Dec 21, 2020 at 10:47:37PM CST, Joel Stanley wrote: >> > >On Tue, 15 Dec 2020 at 02:46, Zev Weiss <zev@bewilderbeest.net> wrote: >> > >> >> > >> Instead of testing and conditionally clearing them one by one, we >> > >> can instead just unconditionally clear them all at once. >> > >> >> > >> Signed-off-by: Zev Weiss <zev@bewilderbeest.net> >> > > >> > >I had a poke at the assembly and it looks like GCC is clearing the >> > >bits unconditionally anyway, so removing the tests provides no change. >> > > >> > >Combining them is a good further optimization. >> > > >> > >Reviewed-by: Joel Stanley <joel@jms.id.au> >> > > >> > >A question unrelated to this patch: Do you know why the driver >> > >doesn't clear the status bits in the interrupt handler? I would >> > >expect it to write the value of sts back to the register to ack the >> > >pending interrupt. >> > > >> > >> > No, I don't, and I was sort of wondering the same thing actually -- >> > I'm not deeply familiar with this hardware or driver though, so I was >> > a bit hesitant to start messing with things. (Though maybe doing so >> > would address the "stickiness" aspect when it does manifest.) Perhaps >> > Eddie or Jae can shed some light here? >> >> I think you're onto something here - this would be why the status bits seem to >> stick until the device is reset. >> >> Until Aspeed can clarify if this is a hardware or software issue, I suggest we ack >> the bits and log a message when we see them, instead of always ignoring them >> without taking any action. >> >> Can you write a patch that changes the interrupt handler to ack status bits as it >> handles each of them? >> >Hello Zev, before the patch, do you met issue with irq handler? [continuous incoming?] > >In aspeed_video_irq handler should only handle enable interrupt expected. > u32 sts = aspeed_video_read(video, VE_INTERRUPT_STATUS); > + sts &= aspeed_video_read(video, VE_INTERRUPT_CTRL); > >Ryan > Hi Ryan, Prior to any of these patches I encountered a problem pretty much exactly like what Jae described in his commit message in 65d270acb2d (but the kernel I was running included that patch). Adding the diagnostic in patch #1 of this series showed that it was apparently the same problem, just with a different interrupt that Jae's patch didn't include. From what you wrote above, I gather that it is in fact expected for the hardware to assert interrupts that aren't enabled in VE_INTERRUPT_CTRL? If so, I guess something like that would obviate the need for both Jae's earlier patch and this whole series. I think the question Joel raised is somewhat independent though -- if the VE_INTERRUPT_STATUS register asserts interrupts we're not actually using, should the driver acknowledge them anyway or just leave them alone? (Though if we're just going to ignore them anyway maybe it doesn't ultimately matter very much.) Zev
> -----Original Message----- > From: Zev Weiss <zev@bewilderbeest.net> > Sent: Wednesday, December 23, 2020 11:54 AM > To: Ryan Chen <ryan_chen@aspeedtech.com> > Cc: Joel Stanley <joel@jms.id.au>; Eddie James <eajames@linux.ibm.com>; > Mauro Carvalho Chehab <mchehab@kernel.org>; Andrew Jeffery > <andrew@aj.id.au>; linux-media@vger.kernel.org; OpenBMC Maillist > <openbmc@lists.ozlabs.org>; Linux ARM > <linux-arm-kernel@lists.infradead.org>; linux-aspeed > <linux-aspeed@lists.ozlabs.org>; Linux Kernel Mailing List > <linux-kernel@vger.kernel.org>; Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> > Subject: Re: [PATCH 2/3] aspeed-video: clear spurious interrupt bits > unconditionally > > On Tue, Dec 22, 2020 at 08:53:33PM CST, Ryan Chen wrote: > >> -----Original Message----- > >> From: Joel Stanley <joel@jms.id.au> > >> Sent: Wednesday, December 23, 2020 9:07 AM > >> To: Zev Weiss <zev@bewilderbeest.net>; Ryan Chen > >> <ryan_chen@aspeedtech.com> > >> Cc: Eddie James <eajames@linux.ibm.com>; Mauro Carvalho Chehab > >> <mchehab@kernel.org>; Andrew Jeffery <andrew@aj.id.au>; > >> linux-media@vger.kernel.org; OpenBMC Maillist > >> <openbmc@lists.ozlabs.org>; Linux ARM > >> <linux-arm-kernel@lists.infradead.org>; linux-aspeed > >> <linux-aspeed@lists.ozlabs.org>; Linux Kernel Mailing List > >> <linux-kernel@vger.kernel.org>; Jae Hyun Yoo > >> <jae.hyun.yoo@linux.intel.com> > >> Subject: Re: [PATCH 2/3] aspeed-video: clear spurious interrupt bits > >> unconditionally > >> > >> On Tue, 22 Dec 2020 at 19:14, Zev Weiss <zev@bewilderbeest.net> wrote: > >> > > >> > On Mon, Dec 21, 2020 at 10:47:37PM CST, Joel Stanley wrote: > >> > >On Tue, 15 Dec 2020 at 02:46, Zev Weiss <zev@bewilderbeest.net> > wrote: > >> > >> > >> > >> Instead of testing and conditionally clearing them one by one, > >> > >> we can instead just unconditionally clear them all at once. > >> > >> > >> > >> Signed-off-by: Zev Weiss <zev@bewilderbeest.net> > >> > > > >> > >I had a poke at the assembly and it looks like GCC is clearing the > >> > >bits unconditionally anyway, so removing the tests provides no change. > >> > > > >> > >Combining them is a good further optimization. > >> > > > >> > >Reviewed-by: Joel Stanley <joel@jms.id.au> > >> > > > >> > >A question unrelated to this patch: Do you know why the driver > >> > >doesn't clear the status bits in the interrupt handler? I would > >> > >expect it to write the value of sts back to the register to ack > >> > >the pending interrupt. > >> > > > >> > > >> > No, I don't, and I was sort of wondering the same thing actually -- > >> > I'm not deeply familiar with this hardware or driver though, so I > >> > was a bit hesitant to start messing with things. (Though maybe > >> > doing so would address the "stickiness" aspect when it does > >> > manifest.) Perhaps Eddie or Jae can shed some light here? > >> > >> I think you're onto something here - this would be why the status > >> bits seem to stick until the device is reset. > >> > >> Until Aspeed can clarify if this is a hardware or software issue, I > >> suggest we ack the bits and log a message when we see them, instead > >> of always ignoring them without taking any action. > >> > >> Can you write a patch that changes the interrupt handler to ack > >> status bits as it handles each of them? > >> > >Hello Zev, before the patch, do you met issue with irq handler? > >[continuous incoming?] > > > >In aspeed_video_irq handler should only handle enable interrupt expected. > > u32 sts = aspeed_video_read(video, VE_INTERRUPT_STATUS); > > + sts &= aspeed_video_read(video, VE_INTERRUPT_CTRL); > > > >Ryan > > > > Hi Ryan, > > Prior to any of these patches I encountered a problem pretty much exactly like > what Jae described in his commit message in 65d270acb2d (but the kernel I > was running included that patch). Adding the diagnostic in patch #1 of this > series showed that it was apparently the same problem, just with a different > interrupt that Jae's patch didn't include. > > From what you wrote above, I gather that it is in fact expected for the > hardware to assert interrupts that aren't enabled in VE_INTERRUPT_CTRL? > If so, I guess something like that would obviate the need for both Jae's earlier > patch and this whole series. > Yes, I expected handle enabled in VE_INTERRUPT_CTRL. > I think the question Joel raised is somewhat independent though -- if the > VE_INTERRUPT_STATUS register asserts interrupts we're not actually using, > should the driver acknowledge them anyway or just leave them alone? My opinion will keep them alone, ignore them. > (Though if we're just going to ignore them anyway maybe it doesn't ultimately > matter very much.) > > > Zev
diff --git a/drivers/media/platform/aspeed-video.c b/drivers/media/platform/aspeed-video.c index eb02043532e3..218aae3be809 100644 --- a/drivers/media/platform/aspeed-video.c +++ b/drivers/media/platform/aspeed-video.c @@ -558,6 +558,14 @@ static void aspeed_video_irq_res_change(struct aspeed_video *video, ulong delay) schedule_delayed_work(&video->res_work, delay); } +/* + * Interrupts that we don't use but have to explicitly ignore because the + * hardware asserts them even when they're disabled in the VE_INTERRUPT_CTRL + * register. + */ +#define VE_SPURIOUS_IRQS \ + (VE_INTERRUPT_CAPTURE_COMPLETE | VE_INTERRUPT_FRAME_COMPLETE) + static irqreturn_t aspeed_video_irq(int irq, void *arg) { struct aspeed_video *video = arg; @@ -630,15 +638,8 @@ static irqreturn_t aspeed_video_irq(int irq, void *arg) aspeed_video_start_frame(video); } - /* - * CAPTURE_COMPLETE and FRAME_COMPLETE interrupts come even when these - * are disabled in the VE_INTERRUPT_CTRL register so clear them to - * prevent unnecessary interrupt calls. - */ - if (sts & VE_INTERRUPT_CAPTURE_COMPLETE) - sts &= ~VE_INTERRUPT_CAPTURE_COMPLETE; - if (sts & VE_INTERRUPT_FRAME_COMPLETE) - sts &= ~VE_INTERRUPT_FRAME_COMPLETE; + /* Squash known bogus interrupts */ + sts &= ~VE_SPURIOUS_IRQS; if (sts) dev_err_ratelimited(video->dev, "unexpected interrupt asserted:"
Instead of testing and conditionally clearing them one by one, we can instead just unconditionally clear them all at once. Signed-off-by: Zev Weiss <zev@bewilderbeest.net> --- drivers/media/platform/aspeed-video.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-)