Re: [PATCH] PCI: Quirk Intel DG2 ASPM L1 acceptable latency to be unlimited

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, Apr 05, 2022 at 12:38:10PM +0300, Mika Westerberg wrote:
> Intel DG2 discrete graphics PCIe endpoints hard-code their acceptable L1
> ASPM latency to be < 1us even though the hardware actually supports
> higher latencies (> 64 us) just fine. In order to allow the links to go
> into L1 and save power, quirk the acceptable L1 ASPM latency for these
> endpoints to be unlimited.
> 
> Note this does not have any effect unless the user requested the kernel
> to enable ASPM in the first place (by default we don't enable it). This
> is done with "pcie_aspm=force pcie_aspm.policy=powersupsersave" command
> line parameters.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
>  drivers/pci/quirks.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index da829274fc66..e97b5daa00eb 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -5895,3 +5895,47 @@ DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1533, rom_bar_overlap_defect);
>  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1536, rom_bar_overlap_defect);
>  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1537, rom_bar_overlap_defect);
>  DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1538, rom_bar_overlap_defect);
> +
> +#ifdef CONFIG_PCIEASPM
> +/*
> + * Intel DG2 graphics card has hard-coded acceptable L1 latency that is
> + * too low which prevents ASPM to be enabled. It does support ASPM L1
> + * and tolerates higher latencies so quirk it to be unlimited.
> + */
> +static void quirk_aspm_accepted_l1_latency(struct pci_dev *dev)
> +{
> +	if ((dev->devcap & PCI_EXP_DEVCAP_L1) >> 9 < 7) {
> +		u32 devcap = dev->devcap;
> +
> +		dev->devcap |= 7 << 9;
> +		pci_info(dev, "quirking devcap for L1 accepted latency 0x%08x -> 0x%08x\n",
> +			 devcap, dev->devcap);
> +	}
> +}
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x4f80, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x4f81, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x4f82, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x4f83, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x4f84, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x4f85, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x4f86, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x4f87, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x4f88, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x5690, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x5691, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x5692, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x5693, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x5694, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x5695, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56a0, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56a1, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56a2, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56a3, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56a4, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56a5, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56a6, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56b0, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56b1, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56c0, quirk_aspm_accepted_l1_latency);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x56c1, quirk_aspm_accepted_l1_latency);
> +#endif

This matches our expectations and IDs.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> -- 
> 2.35.1
>