[Intel-gfx] [PATCH] drm/i915/guc: Reduce verbosity on log overflows

[Chris Wilson]

Quoting Michal Wajdeczko (2019-06-17 15:38:53)
> On Mon, 17 Jun 2019 12:09:17 +0200, Chris Wilson  
> <chris at chris-wilson.co.uk> wrote:
> 
> > If the user is clearing the log buffer too slowly, we overflow. As this
> > is an expected condition, and the driver tries to handle it, reduce the
> > error message down to a notice.
> >
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110817
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_guc_log.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_guc_log.c  
> > b/drivers/gpu/drm/i915/intel_guc_log.c
> > index bf1446629703..e3b83ecb90b5 100644
> > --- a/drivers/gpu/drm/i915/intel_guc_log.c
> > +++ b/drivers/gpu/drm/i915/intel_guc_log.c
> > @@ -208,7 +208,9 @@ static bool guc_check_log_buf_overflow(struct  
> > intel_guc_log *log,
> >                       /* buffer_full_cnt is a 4 bit counter */
> >                       log->stats[type].sampled_overflow += 16;
> >               }
> > -             DRM_ERROR_RATELIMITED("GuC log buffer overflow\n");
> > +
> > +             dev_notice_ratelimited(guc_to_i915(log_to_guc(log))->drm.dev,
> > +                                    "GuC log buffer overflow\n");
> 
> While this change alone is not harmful, I'm afraid that there might
> be another reason why we see this message : once buffer_full_cnt is
> turned on by the fw and then we reset the Guc, this field may have
> stale value as it is not cleared by us/uc and we may wrongly assume
> that there was an overflow.

Fwiw, at the moment, it is being thrown by the cat /debug/dri/0/* test.
-Chris