[Intel-gfx] [PATCH] drm/i915: Show debugfs dpcd read failure directly

[Dhinakaran Pandiyan]

On Fri, 2018-07-20 at 10:41 -0700, Rodrigo Vivi wrote:
> Instead of using a backchannel if some dpcd read failed we
> can show that directly on debugfs output.
> 
> We are not returning an error because we might still want
> to know if sub-sequent reads works,

We can print partial ( and successful) output and return the first
error value we get.

We should probably get rid of that warn_on too.

>  but we shouldn't
> need to check 2 places to see why reg is not on the list.
> 
> Cc: Jani Nikula <jani.nikula at intel.com>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c
> b/drivers/gpu/drm/i915/i915_debugfs.c
> index 59dc0610ea44..5d8da4e8c444 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4846,8 +4846,8 @@ static int i915_dpcd_show(struct seq_file *m,
> void *data)
>  
>  		err = drm_dp_dpcd_read(&intel_dp->aux, b->offset,
> buf, size);
>  		if (err <= 0) {
> -			DRM_ERROR("dpcd read (%zu bytes at %u)
> failed (%zd)\n",
> -				  size, b->offset, err);
> +			seq_printf(m, "dpcd read (%zu bytes at %u)
> failed (%zd)\n",
> +				   size, b->offset, err);
>  			continue;
>  		}
>