[Intel-gfx] [PATCH] drm/i915: Spam less on dp aux send/receive problems

[Jani Nikula]

On Thu, 06 Aug 2015, Mika Kuoppala <mika.kuoppala at linux.intel.com> wrote:
> If we encounter frequent problems with dp aux channel
> communications, we end up spamming the dmesg with the
> exact similar trace and status.
>
> Inject a new backtrace only if we have new information
> to share as otherwise we flush out all other important
> stuff.
>
> Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index df7e2cf..6b2f7af 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -849,8 +849,15 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
>  	}
>  
>  	if (try == 3) {
> -		WARN(1, "dp_aux_ch not started status 0x%08x\n",
> -		     I915_READ(ch_ctl));
> +		static u32 last_status = -1;
> +		const u32 status = I915_READ(ch_ctl);
> +
> +		if (status != last_status) {
> +			WARN(1, "dp_aux_ch not started status 0x%08x\n",
> +			     status);
> +			last_status = status;
> +		}
> +

But now you'll also skip the logging even if there's been a day and a
million successful transfers since the last error... I understand your
concern, but if you feel you must do something like this, please at
least reset last_status on success.

BR,
Jani.


>  		ret = -EBUSY;
>  		goto out;
>  	}
> -- 
> 2.1.4
>
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-- 
Jani Nikula, Intel Open Source Technology Center