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SubjectRe: [PATCH v1 1/2] PCI/ASPM: Disable ASPM L1.2 Substate if we don't have LTR
Hi Bjorn,

I have verified this patch, it works fine for me.

Thanks & Regards,
Srinath.

On Fri, Apr 20, 2018 at 2:35 AM, Bjorn Helgaas <helgaas@kernel.org> wrote:
> From: Bjorn Helgaas <bhelgaas@google.com>
>
> When in the ASPM L1.0 state (but not the PCI-PM L1.0 state), the most
> recent LTR value and the LTR_L1.2_THRESHOLD determines whether the link
> enters the L1.2 substate.
>
> If we don't have LTR enabled, prevent the use of ASPM L1.2.
>
> PCI-PM L1.2 may still be used because it doesn't depend on
> LTR_L1.2_THRESHOLD (see PCIe r4.0, sec 5.5.1).
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
> ---
> drivers/pci/pcie/aspm.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
> index f76eb7704f64..c687c817b47d 100644
> --- a/drivers/pci/pcie/aspm.c
> +++ b/drivers/pci/pcie/aspm.c
> @@ -400,6 +400,15 @@ static void pcie_get_aspm_reg(struct pci_dev *pdev,
> info->l1ss_cap = 0;
> return;
> }
> +
> + /*
> + * If we don't have LTR for the entire path from the Root Complex
> + * to this device, we can't use ASPM L1.2 because it relies on the
> + * LTR_L1.2_THRESHOLD. See PCIe r4.0, secs 5.5.4, 6.18.
> + */
> + if (!pdev->ltr_path)
> + info->l1ss_cap &= ~PCI_L1SS_CAP_ASPM_L1_2;
> +
> pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL1,
> &info->l1ss_ctl1);
> pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL2,
>

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