On 11/02/2022 20:27, alyssa.rosenzweig@xxxxxxxxxxxxx wrote: > From: Alyssa Rosenzweig <alyssa.rosenzweig@xxxxxxxxxxxxx> > > TTRX_3485 requires the infamous "dummy job" workaround. I have this > workaround implemented in a local branch, but I have not yet hit a case > that requires it so I cannot test whether the implementation is correct. > In the mean time, add the quirk bit so we can document which platforms > may need it in the future. This one is hideous ;) Although to me this isn't the 'infamous' one as it's not the earliest example of a dummy job. However... I believe as Panfrost currently stands this is probably not very possible to hit. It requires a job to be stopped (soft or hard) at a critical point during submission - which at the moment Panfrost basically never does (the exception is if you close the fd immediately while a job is in progress). And of course the timing has to be 'just right' to hit the bug. That said I think we should probably add pre-emption support sometime at which point this could become an issue. > Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@xxxxxxxxxxxxx> Reviewed-by: Steven Price <steven.price@xxxxxxx> > --- > drivers/gpu/drm/panfrost/panfrost_issues.h | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/panfrost/panfrost_issues.h b/drivers/gpu/drm/panfrost/panfrost_issues.h > index 058f6a4c8435..b8865fc9efce 100644 > --- a/drivers/gpu/drm/panfrost/panfrost_issues.h > +++ b/drivers/gpu/drm/panfrost/panfrost_issues.h > @@ -132,6 +132,9 @@ enum panfrost_hw_issue { > * to hang */ > HW_ISSUE_TTRX_3076, > > + /* Must issue a dummy job before starting real work to prevent hangs */ > + HW_ISSUE_TTRX_3485, > + > HW_ISSUE_END > }; >