Re: [PATCH 2/3] PCI/ASPM: Fix L0s max latency check

[Ian Kumlien <ian.kumlien@gmail.com>]

*bump*

On Sat, Oct 24, 2020 at 10:55 PM Ian Kumlien <ian.kumlien@gmail.com> wrote:
>
> From what I have been able to figure out, it seems like LOs path latency
> is cumulative, so the max path latency should be the sum of all links
> maximum latency.
>
> Signed-off-by: Ian Kumlien <ian.kumlien@gmail.com>
> ---
>  drivers/pci/pcie/aspm.c | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index c03ead0f1013..dbe3ce60c1ff 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -434,7 +434,8 @@ static void pcie_get_aspm_reg(struct pci_dev *pdev,
>
>  static void pcie_aspm_check_latency(struct pci_dev *endpoint)
>  {
> -       u32 latency, l1_max_latency = 0, l1_switch_latency = 0;
> +       u32 latency, l1_max_latency = 0, l1_switch_latency = 0,
> +               l0s_latency_up = 0, l0s_latency_dw = 0;
>         struct aspm_latency *acceptable;
>         struct pcie_link_state *link;
>
> @@ -448,14 +449,18 @@ static void pcie_aspm_check_latency(struct pci_dev *endpoint)
>
>         while (link) {
>                 /* Check upstream direction L0s latency */
> -               if ((link->aspm_capable & ASPM_STATE_L0S_UP) &&
> -                   (link->latency_up.l0s > acceptable->l0s))
> -                       link->aspm_capable &= ~ASPM_STATE_L0S_UP;
> +               if (link->aspm_capable & ASPM_STATE_L0S_UP) {
> +                       l0s_latency_up += link->latency_up.l0s;
> +                       if (l0s_latency_up > acceptable->l0s)
> +                               link->aspm_capable &= ~ASPM_STATE_L0S_UP;
> +               }
>
>                 /* Check downstream direction L0s latency */
> -               if ((link->aspm_capable & ASPM_STATE_L0S_DW) &&
> -                   (link->latency_dw.l0s > acceptable->l0s))
> -                       link->aspm_capable &= ~ASPM_STATE_L0S_DW;
> +               if (link->aspm_capable & ASPM_STATE_L0S_DW) {
> +                       l0s_latency_dw += link->latency_dw.l0s;
> +                       if (l0s_latency_dw > acceptable->l0s)
> +                               link->aspm_capable &= ~ASPM_STATE_L0S_DW;
> +               }
>
>                 /*
>                  * Check L1 latency.
> --
> 2.29.1
>