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From: Tuikov, Luben <Luben.Tuikov@xxxxxxx>
Sent: Friday, April 8, 2022 9:33 AM To: Powell, Darren <Darren.Powell@xxxxxxx>; amd-gfx@xxxxxxxxxxxxxxxxxxxxx <amd-gfx@xxxxxxxxxxxxxxxxxxxxx> Cc: Quan, Evan <Evan.Quan@xxxxxxx>; Wenhui.Sheng@xxxxxxx <Wenhui.Sheng@xxxxxxx>; Grodzovsky, Andrey <Andrey.Grodzovsky@xxxxxxx> Subject: Re: [PATCH 1/1] amdgpu/pm: Clarify Documentation of error handling in send_smc_mesg I'd add who and how is the message dropped, and also mention that we're unable
to recognize a dropped message. On 2022-04-07 22:26, Darren Powell wrote: > Contrary to the smu_cmn_send_smc_msg_with_param documentation, two > cases exist where messages are silently dropped with no error returned > to the caller. These cases occur in unusual situations where either: > 1. the caller is a virtual GPU, or The caller? Isn't this code executed on a CPU sending to the SMU (which lives on a GPU)? [DP] Great point, will fix > 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") > > Signed-off-by: Darren Powell <darren.powell@xxxxxxx> > --- > drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 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..b1bd1990c88b 100644 > --- a/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c > +++ b/drivers/gpu/drm/amd/pm/swsmu/smu_cmn.c > @@ -356,12 +356,15 @@ 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 > + * Return 0 on success, or if the message is dropped. > + * On error, -errno is returned if we weren't able to send Something like this: Return 0 on success, -errno on error. If the message was dropped due to PCI bus recovery or sending to a virtual GPU, we're unable to detect this and success is also returned. > * the message or if the message completed with some kind of > * error. 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. > + * the error to the standard log. Dropped messages can be caused > + * due to PCI slot recovery or attempting to send from a virtual GPU, > + * and do not print an error. This is a moot point with the clarification I suggested above and I'd remove that. [DP] sounds more succinct, will address in v2 > * > * Command completion status is printed only if the -errno is > * -EREMOTEIO, indicating that the SMU returned back an > > base-commit: 4585c45a6a66cb17cc97f4370457503746e540b7 Regards, -- Luben |
