drm/i915: if transcoder disable fails, say which

Just some extra debug output.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-By: Eugeni Dodonov <eugeni.dodonov@intel.com>
Reviewed-By: Eugeni Dodonov <eugeni.dodonov@intel.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 064c659..921253c 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1276,7 +1276,7 @@
 	I915_WRITE(reg, val);
 	/* wait for PCH transcoder off, transcoder state */
 	if (wait_for((I915_READ(reg) & TRANS_STATE_ENABLE) == 0, 50))
-		DRM_ERROR("failed to disable transcoder\n");
+		DRM_ERROR("failed to disable transcoder %d\n", pipe);
 }
 
 /**