Re: [PATCH V2] PCI/ASPM: Save/restore L1SS Capability for suspend/resume

From: Kai-Heng Feng
Date: Thu Jul 14 2022 - 00:21:23 EST

On Thu, Jul 14, 2022 at 2:16 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>
> [+cc Kai-Heng]
>
> On Wed, Jul 13, 2022 at 11:29:42PM +0530, Vidya Sagar wrote:
> > Hi,
> > @Kenneth, Could you please verify it on your laptop one last time?
> >
> > @Bjorn, Could you please review this change in the meanwhile?
>
> Seems like this may be related to Kai-Heng's patch:
> https://lore.kernel.org/r/20220509073639.2048236-1-kai.heng.feng@xxxxxxxxxxxxx
> since he specifically mentioned L1SS.

Yes, to make L1ss restore successful on system resume this patch is also needed.

Kai-Heng

>
> I applied Kai-Heng's patch for v5.20 yesterday, but I haven't worked
> out the connection to this patch. But if you want Kenneth to test
> this, it should probably be on top of Kai-Heng's patch so we're
> testing something close to the eventual result.
>
> > On 7/5/2022 11:30 AM, Vidya Sagar wrote:
> > > External email: Use caution opening links or attachments
> > >
> > >
> > > Previously ASPM L1 Substates control registers (CTL1 and CTL2) weren't
> > > saved and restored during suspend/resume leading to L1 Substates
> > > configuration being lost post-resume.
> > >
> > > Save the L1 Substates control registers so that the configuration is
> > > retained post-resume.
> > >
> > > Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
> > > Tested-by: Abhishek Sahu <abhsahu@xxxxxxxxxx>
> > > ---
> > > Hi,
> > > Kenneth R. Crudup <kenny@xxxxxxxxx>, Could you please verify this patch
> > > on your laptop (Dell XPS 13) one last time?
> > > IMHO, the regression observed on your laptop with an old version of the patch
> > > could be due to a buggy old version BIOS in the laptop.
> > >
> > > Thanks,
> > > Vidya Sagar
> > >
> > > drivers/pci/pci.c | 7 +++++++
> > > drivers/pci/pci.h | 4 ++++
> > > drivers/pci/pcie/aspm.c | 44 +++++++++++++++++++++++++++++++++++++++++
> > > 3 files changed, 55 insertions(+)
> > >
> > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > > index cfaf40a540a8..aca05880aaa3 100644
> > > --- a/drivers/pci/pci.c
> > > +++ b/drivers/pci/pci.c
> > > @@ -1667,6 +1667,7 @@ int pci_save_state(struct pci_dev *dev)
> > > return i;
> > >
> > > pci_save_ltr_state(dev);
> > > + pci_save_aspm_l1ss_state(dev);
> > > pci_save_dpc_state(dev);
> > > pci_save_aer_state(dev);
> > > pci_save_ptm_state(dev);
> > > @@ -1773,6 +1774,7 @@ void pci_restore_state(struct pci_dev *dev)
> > > * LTR itself (in the PCIe capability).
> > > */
> > > pci_restore_ltr_state(dev);
> > > + pci_restore_aspm_l1ss_state(dev);
> > >
> > > pci_restore_pcie_state(dev);
> > > pci_restore_pasid_state(dev);
> > > @@ -3489,6 +3491,11 @@ void pci_allocate_cap_save_buffers(struct pci_dev *dev)
> > > if (error)
> > > pci_err(dev, "unable to allocate suspend buffer for LTR\n");
> > >
> > > + error = pci_add_ext_cap_save_buffer(dev, PCI_EXT_CAP_ID_L1SS,
> > > + 2 * sizeof(u32));
> > > + if (error)
> > > + pci_err(dev, "unable to allocate suspend buffer for ASPM-L1SS\n");
> > > +
> > > pci_allocate_vc_save_buffers(dev);
> > > }
> > >
> > > diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> > > index e10cdec6c56e..92d8c92662a4 100644
> > > --- a/drivers/pci/pci.h
> > > +++ b/drivers/pci/pci.h
> > > @@ -562,11 +562,15 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev);
> > > void pcie_aspm_exit_link_state(struct pci_dev *pdev);
> > > void pcie_aspm_pm_state_change(struct pci_dev *pdev);
> > > void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
> > > +void pci_save_aspm_l1ss_state(struct pci_dev *dev);
> > > +void pci_restore_aspm_l1ss_state(struct pci_dev *dev);
> > > #else
> > > static inline void pcie_aspm_init_link_state(struct pci_dev *pdev) { }
> > > static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev) { }
> > > static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev) { }
> > > static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev) { }
> > > +static inline void pci_save_aspm_l1ss_state(struct pci_dev *dev) { }
> > > +static inline void pci_restore_aspm_l1ss_state(struct pci_dev *dev) { }
> > > #endif
> > >
> > > #ifdef CONFIG_PCIE_ECRC
> > > diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> > > index a96b7424c9bc..2c29fdd20059 100644
> > > --- a/drivers/pci/pcie/aspm.c
> > > +++ b/drivers/pci/pcie/aspm.c
> > > @@ -726,6 +726,50 @@ static void pcie_config_aspm_l1ss(struct pcie_link_state *link, u32 state)
> > > PCI_L1SS_CTL1_L1SS_MASK, val);
> > > }
> > >
> > > +void pci_save_aspm_l1ss_state(struct pci_dev *dev)
> > > +{
> > > + int aspm_l1ss;
> > > + struct pci_cap_saved_state *save_state;
> > > + u32 *cap;
> > > +
> > > + if (!pci_is_pcie(dev))
> > > + return;
> > > +
> > > + aspm_l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS);
> > > + if (!aspm_l1ss)
> > > + return;
> > > +
> > > + save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_L1SS);
> > > + if (!save_state)
> > > + return;
> > > +
> > > + cap = (u32 *)&save_state->cap.data[0];
> > > + pci_read_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL2, cap++);
> > > + pci_read_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL1, cap++);
> > > +}
> > > +
> > > +void pci_restore_aspm_l1ss_state(struct pci_dev *dev)
> > > +{
> > > + int aspm_l1ss;
> > > + struct pci_cap_saved_state *save_state;
> > > + u32 *cap;
> > > +
> > > + if (!pci_is_pcie(dev))
> > > + return;
> > > +
> > > + aspm_l1ss = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_L1SS);
> > > + if (!aspm_l1ss)
> > > + return;
> > > +
> > > + save_state = pci_find_saved_ext_cap(dev, PCI_EXT_CAP_ID_L1SS);
> > > + if (!save_state)
> > > + return;
> > > +
> > > + cap = (u32 *)&save_state->cap.data[0];
> > > + pci_write_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL2, *cap++);
> > > + pci_write_config_dword(dev, aspm_l1ss + PCI_L1SS_CTL1, *cap++);
> > > +}
> > > +
> > > static void pcie_config_aspm_dev(struct pci_dev *pdev, u32 val)
> > > {
> > > pcie_capability_clear_and_set_word(pdev, PCI_EXP_LNKCTL,
> > > --
> > > 2.17.1
> > >