| Message ID | 20240216062559.247479-3-jhp@endlessos.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v4,1/3] PCI: vmd: Enable PCI PM's L1 substates of remapped PCIe Root Port and NVMe | expand |
In subject: PCI/ASPM: Document D0 requirement when enabling PCI-PM L1 PM Substates On Fri, Feb 16, 2024 at 02:26:01PM +0800, Jian-Hong Pan wrote: > According to PCI Express Base Specification Revision 6.0, Section 5.5.4: > "If setting either or both of the enable bits for PCI-PM L1 PM Substates, > both ports must be configured as described in this section while in D0." "PCIe r6.0, sec 5.5.4" is enough. > Add notes into pci_enable_link_state(_locked) for kernel-doc. Add note about D0 requirement in pci_enable_link_state() kernel-doc. > Hope these > notify callers ensuring the devices in D0, if PCI-PM L1 PM Substates are > going to be enabled. Skip this part. > Signed-off-by: Jian-Hong Pan <jhp@endlessos.org> With above updates, Acked-by: Bjorn Helgaas <bhelgaas@google.com> > --- > v3: > - Fix as readable comments > > v4: > - The same > > drivers/pci/pcie/aspm.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c > index 7f1d674ff171..a39d2ee744cb 100644 > --- a/drivers/pci/pcie/aspm.c > +++ b/drivers/pci/pcie/aspm.c > @@ -1416,6 +1416,9 @@ static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) > * touch the LNKCTL register. Also note that this does not enable states > * disabled by pci_disable_link_state(). Return 0 or a negative errno. > * > + * Note: Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per > + * PCIe r6.0, sec 5.5.4. > + * > * @pdev: PCI device > * @state: Mask of ASPM link states to enable > */ > @@ -1432,6 +1435,9 @@ EXPORT_SYMBOL(pci_enable_link_state); > * can't touch the LNKCTL register. Also note that this does not enable states > * disabled by pci_disable_link_state(). Return 0 or a negative errno. > * > + * Note: Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per > + * PCIe r6.0, sec 5.5.4. > + * > * @pdev: PCI device > * @state: Mask of ASPM link states to enable > * > -- > 2.43.2 >
On 2/15/24 10:26 PM, Jian-Hong Pan wrote: > According to PCI Express Base Specification Revision 6.0, Section 5.5.4: > "If setting either or both of the enable bits for PCI-PM L1 PM Substates, > both ports must be configured as described in this section while in D0." > > Add notes into pci_enable_link_state(_locked) for kernel-doc. Hope these > notify callers ensuring the devices in D0, if PCI-PM L1 PM Substates are > going to be enabled. > > Signed-off-by: Jian-Hong Pan <jhp@endlessos.org> > --- Looks fine to me. Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> > v3: > - Fix as readable comments > > v4: > - The same > > drivers/pci/pcie/aspm.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c > index 7f1d674ff171..a39d2ee744cb 100644 > --- a/drivers/pci/pcie/aspm.c > +++ b/drivers/pci/pcie/aspm.c > @@ -1416,6 +1416,9 @@ static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) > * touch the LNKCTL register. Also note that this does not enable states > * disabled by pci_disable_link_state(). Return 0 or a negative errno. > * > + * Note: Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per > + * PCIe r6.0, sec 5.5.4. > + * > * @pdev: PCI device > * @state: Mask of ASPM link states to enable > */ > @@ -1432,6 +1435,9 @@ EXPORT_SYMBOL(pci_enable_link_state); > * can't touch the LNKCTL register. Also note that this does not enable states > * disabled by pci_disable_link_state(). Return 0 or a negative errno. > * > + * Note: Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per > + * PCIe r6.0, sec 5.5.4. > + * > * @pdev: PCI device > * @state: Mask of ASPM link states to enable > *
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 7f1d674ff171..a39d2ee744cb 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1416,6 +1416,9 @@ static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) * touch the LNKCTL register. Also note that this does not enable states * disabled by pci_disable_link_state(). Return 0 or a negative errno. * + * Note: Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per + * PCIe r6.0, sec 5.5.4. + * * @pdev: PCI device * @state: Mask of ASPM link states to enable */ @@ -1432,6 +1435,9 @@ EXPORT_SYMBOL(pci_enable_link_state); * can't touch the LNKCTL register. Also note that this does not enable states * disabled by pci_disable_link_state(). Return 0 or a negative errno. * + * Note: Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per + * PCIe r6.0, sec 5.5.4. + * * @pdev: PCI device * @state: Mask of ASPM link states to enable *
According to PCI Express Base Specification Revision 6.0, Section 5.5.4: "If setting either or both of the enable bits for PCI-PM L1 PM Substates, both ports must be configured as described in this section while in D0." Add notes into pci_enable_link_state(_locked) for kernel-doc. Hope these notify callers ensuring the devices in D0, if PCI-PM L1 PM Substates are going to be enabled. Signed-off-by: Jian-Hong Pan <jhp@endlessos.org> --- v3: - Fix as readable comments v4: - The same drivers/pci/pcie/aspm.c | 6 ++++++ 1 file changed, 6 insertions(+)