[PATCH 1/1] amdgpu/pm: Clarify documentation of error handling in send_smc_mesg

[Luben Tuikov]

I suppose I didn't quite register this on a first read:

On 2022-04-12 00:08, Darren Powell wrote:
> Contrary to the smu_cmn_send_smc_msg_with_param documentation, two

I'd just say

  Clarify the documentation to also mention that we drop
  messages and return success in the following two cases:
     1. ...

That "Contrary to the ..." sounds a bit harsh.

Regards,
Luben

> cases exist where messages are silently dropped with no error returned
> to the caller. These cases occur in unusual situations where either:
>  1. the message target is a virtual GPU, or
>  2. a PCI recovery is underway and the HW is not yet in sync with the SW
> 
> For more details see
>  commit 4ea5081c82c4 ("drm/amd/powerplay: enable SMC message filter")
>  commit bf36b52e781d ("drm/amdgpu: Avoid accessing HW when suspending SW state")
> 
> (v2)
>   Reworked with suggestions from Luben & Paul
> 
> Signed-off-by: Darren Powell <darren.powell at amd.com>
> ---
>  drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
> index b8d0c70ff668..8008ae5508e6 100644
> --- a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
> +++ b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c
> @@ -356,9 +356,11 @@ int smu_cmn_wait_for_response(struct smu_context *smu)
>   * completion of the command, and return back a value from the SMU in
>   * @read_arg pointer.
>   *
> - * Return 0 on success, -errno on error, if we weren't able to send
> - * the message or if the message completed with some kind of
> - * error. See __smu_cmn_reg2errno() for details of the -errno.
> + * Return 0 on success, -errno when a problem is encountered sending
> + * message or receiving reply. If there is a PCI bus recovery or
> + * the destination is a virtual GPU, the message is simply dropped and
> + * success is also returned.
> + * See __smu_cmn_reg2errno() for details of the -errno.
>   *
>   * If we weren't able to send the message to the SMU, we also print
>   * the error to the standard log.
> 
> base-commit: 4585c45a6a66cb17cc97f4370457503746e540b7

Regards,
-- 
Luben