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

[Michal Wajdeczko]

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.

>  	}
> 	return overflow;