Re: [PATCH 1/3] drm/amd/pm/smu11: BACO is supported when it's in BACO state

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc Stefan, linux-pci]

On Wed, Nov 23, 2022 at 09:43:07AM +0800, Guchun Chen wrote:
> Return true early if ASIC is in BACO state already, no need
> to talk to SMU. It can fix the issue that driver was not
> calling BACO exit at all in runtime pm resume, and a timing
> issue leading to a PCI AER error happened eventually.

This sounds suspiciously racy.

> Fixes: 8795e182b02d ("PCI/portdrv: Don't disable AER reporting in get_port_device_capability()")

To clarify, this patch avoids a driver problem, not a problem with
8795e182b02d.

See question below.

> Suggested-by: Lijo Lazar <lijo.lazar@amd.com>
> Signed-off-by: Guchun Chen <guchun.chen@amd.com>
> ---
>  drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c b/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c
> index 70b560737687..ad5f6a15a1d7 100644
> --- a/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c
> +++ b/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c
> @@ -1588,6 +1588,10 @@ bool smu_v11_0_baco_is_support(struct smu_context *smu)
>  	if (amdgpu_sriov_vf(smu->adev) || !smu_baco->platform_support)
>  		return false;
>  
> +	/* return true if ASIC is in BACO state already */
> +	if (smu_v11_0_baco_get_state(smu) == SMU_BACO_STATE_ENTER)
> +		return true;

smu_v13_0_baco_is_support() is essentially identical to
smu_v11_0_baco_is_support().  Does it need a similar change?

>  	/* Arcturus does not support this bit mask */
>  	if (smu_cmn_feature_is_supported(smu, SMU_FEATURE_BACO_BIT) &&
>  	   !smu_cmn_feature_is_enabled(smu, SMU_FEATURE_BACO_BIT))
> -- 
> 2.25.1
>