[PATCH v4 1/2] PCI: add AMD PCIe quirk for nvme shutdown opt

[Bjorn Helgaas]

[+cc linux-pci, Rafael, thread at
https://lore.kernel.org/linux-nvme/1618458725-17164-1-git-send-email-Prike.Liang@amd.com/#t]

On Thu, Apr 15, 2021 at 11:52:04AM +0800, Prike Liang wrote:
> The NVME device pluged in some AMD PCIE root port will resume timeout
> from s2idle which caused by NVME power CFG lost in the SMU FW restore.
> This issue can be workaround by using PCIe power set with simple
> suspend/resume process path instead of APST. In the onwards ASIC will
> try do the NVME shutdown save and restore in the BIOS and still need PCIe
> power setting to resume from RTD3 for s2idle.
> 
> In this preparation patch add a PCIe quirk for the AMD.

This needs to be cc'd to linux-pci (I did it for you this time).

Sorry, I can't make any sense out of the commit log.  Is this a Root
Port defect or an NVMe device defect?

Patch 2/2 only uses PCI_DEV_FLAGS_AMD_NVME_SIMPLE_SUSPEND in the nvme
driver, so AFAICT there is no reason for the PCI core to keep track of
the flag for you.

I see below that Christoph suggests it needs to be in the PCI core,
but the reason needs to be explained in the commit log.

I have not acked this patch.  Please don't merge it before clearing
these things up.

> Cc: <stable at vger.kernel.org> # 5.11+
> Signed-off-by: Prike Liang <Prike.Liang at amd.com>
> Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k at amd.com>
> [ck: split patches for nvme and pcie]
> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
> 
> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
> ---
> Changes in v2:
> Fix the patch format and check chip root complex DID instead of PCIe RP
> to avoid the storage device plugged in internal PCIe RP by USB adaptor.
> 
> Changes in v3:
> According to Christoph Hellwig do NVME PCIe related identify opt better 
> in PCIe quirk driver rather than in NVME module.
> 
> Changes in v4:
> Split the fix to PCIe and NVMe part and then call the pci_dev_put() put 
> the device reference count and finally refine the commit info.
> ---
> drivers/pci/quirks.c | 10 ++++++++++
>  include/linux/pci.h  |  2 ++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 653660e3..f95c8b2 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -312,6 +312,16 @@ static void quirk_nopciamd(struct pci_dev *dev)
>  }
>  DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD,	PCI_DEVICE_ID_AMD_8151_0,	quirk_nopciamd);
>  
> +static void quirk_amd_nvme_fixup(struct pci_dev *dev)
> +{
> +	struct pci_dev *rdev;
> +
> +	dev->dev_flags |= PCI_DEV_FLAGS_AMD_NVME_SIMPLE_SUSPEND;
> +	pci_info(dev, "AMD simple suspend opt enabled\n");
> +
> +}
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_AMD, 0x1630, quirk_amd_nvme_fixup);
> +
>  /* Triton requires workarounds to be used by the drivers */
>  static void quirk_triton(struct pci_dev *dev)
>  {
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 53f4904..a6e1b1b 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -227,6 +227,8 @@ enum pci_dev_flags {
>  	PCI_DEV_FLAGS_NO_FLR_RESET = (__force pci_dev_flags_t) (1 << 10),
>  	/* Don't use Relaxed Ordering for TLPs directed at this device */
>  	PCI_DEV_FLAGS_NO_RELAXED_ORDERING = (__force pci_dev_flags_t) (1 << 11),
> +	/* AMD simple suspend opt quirk */
> +	PCI_DEV_FLAGS_AMD_NVME_SIMPLE_SUSPEND = (__force pci_dev_flags_t) (1 << 12),
>  };
>  
>  enum pci_irq_reroute_variant {
> -- 
> 2.7.4
> 
> 
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