Re: [PATCH] drm/i915: provide more error output when mode sets fail

[Chris Wilson <chris@chris-wilson.co.uk>]

On Tue, 19 Jul 2011 15:38:56 -0700, Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
> If a mode set fails we may get a message from drm_crtc_helper if we're lucky,
> but it won't tell us anything about *why* we failed to set a mode.  So
> add a few DRM_ERRORs for the cases that shouldn't happen so we can debug
> things more easily.

Also fix drm not to simply ignore the error codes would also be useful.
But how does logging the error without logging the state help? Presumably
you are targeting the unreproducible cases?

> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> ---
>  drivers/gpu/drm/i915/intel_display.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 0f1c799..2434441 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -1934,7 +1934,7 @@ intel_pipe_set_base(struct drm_crtc *crtc, int x, int y,
>  
>  	/* no fb bound */
>  	if (!crtc->fb) {
> -		DRM_DEBUG_KMS("No FB bound\n");
> +		DRM_ERROR("No FB bound\n");
>  		return 0;
>  	}

Should this be flagged as en error then?

>  
> @@ -1943,6 +1943,7 @@ intel_pipe_set_base(struct drm_crtc *crtc, int x, int y,
>  	case 1:
>  		break;
>  	default:
> +		DRM_ERROR("no plane for crtc\n");
>  		return -EINVAL;
>  	}
>  
> @@ -1952,6 +1953,7 @@ intel_pipe_set_base(struct drm_crtc *crtc, int x, int y,
>  					 NULL);
>  	if (ret != 0) {
>  		mutex_unlock(&dev->struct_mutex);
> +		DRM_ERROR("pin & fence failed\n");

In this and the following, report the reason/error code for the failure.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre