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

[Vidya Sagar <vidyas@nvidia.com>]

Hi,
@Kenneth, Could you please verify it on your laptop one last time?

@Bjorn, Could you please review this change in the meanwhile?

Thanks,
Vidya Sagar

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@nvidia.com>
> Tested-by: Abhishek Sahu <abhsahu@nvidia.com>
> ---
> Hi,
> Kenneth R. Crudup <kenny@panix.com>, 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
>