On 1/3/2024 2:35 AM, Vidya Sagar wrote:
> Many PCIe device drivers save the configuration state of their respective
> devices during probe and restore the same when their 'slot_reset' hook
> is called through PCIe Error Recovery System.
Recovery System -> Recovery Handler?
>
> If the system has a change in ASPM policy after the driver's probe is
> called and before error event occurred, 'slot_reset' hook restores the
> PCIe configuration state to what it was at the time of probe but not with
> what it was just before the occurrence of the error event.
> This effectively leads to a mismatch in the ASPM configuration between
> the device and its upstream parent device.
>
> Update the saved configuration state of the device with the latest info
> whenever there is a change w.r.t ASPM policy.
>
> Signed-off-by: Vidya Sagar <vidyas@xxxxxxxxxx>
> ---
> V2:
> * Rebased on top of the tree code
> * Addressed Bjorn's review comments
>
> drivers/pci/pcie/aspm.c | 26 +++++++++++++++++++++++++-
> 1 file changed, 25 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index 67b13f26ba7c..d247cabb5e4c 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -138,16 +138,36 @@ static int policy_to_clkpm_state(struct pcie_link_state *link)
> return 0;
> }
>
> +static void pci_save_aspm_state(struct pci_dev *dev)
> +{
> + int i = 0;
I don't see a need for this variable. You can use index directly.
> + struct pci_cap_saved_state *save_state;
> + u16 *cap;
> +
> + if (!pci_is_pcie(dev))
> + return;
> +
> + save_state = pci_find_saved_cap(dev, PCI_CAP_ID_EXP);
> + if (!save_state)
> + return;
> +
> + cap = (u16 *)&save_state->cap.data[0];
> + i++;
> + pcie_capability_read_word(dev, PCI_EXP_LNKCTL, &cap[i++]);
> +}
> +
> static void pcie_set_clkpm_nocheck(struct pcie_link_state *link, int enable)
> {
> struct pci_dev *child;
> struct pci_bus *linkbus = link->pdev->subordinate;
> u32 val = enable ? PCI_EXP_LNKCTL_CLKREQ_EN : 0;
>
> - list_for_each_entry(child, &linkbus->devices, bus_list)
> + list_for_each_entry(child, &linkbus->devices, bus_list) {
> pcie_capability_clear_and_set_word(child, PCI_EXP_LNKCTL,
> PCI_EXP_LNKCTL_CLKREQ_EN,
> val);
> + pci_save_aspm_state(child);
> + }
> link->clkpm_enabled = !!enable;
> }
>
> @@ -767,6 +787,10 @@ static void pcie_config_aspm_link(struct pcie_link_state *link, u32 state)
> pcie_config_aspm_dev(parent, upstream);
>
> link->aspm_enabled = state;
> +
> + /* Update latest ASPM configuration in saved context */
> + pci_save_aspm_state(link->downstream);
> + pci_save_aspm_state(parent);
> }
>
> static void pcie_config_aspm_path(struct pcie_link_state *link)
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
