[PATCH 3/3] gpu/drm: Add drm_notice logging when drm_mode_create fails

[Jan Niedziolka]

Add logging to have it printed when mode creating fails. As the NULL return has
been present here for a long time, it's better to keep it as it is. However, a
simple drm_notice() print should be helpful when such fail happens.
At the same time, adding drm_notice() to drm_mode_duplicate() allows making use
of *dev parameter and at the same time, keeps the further drm_mode_duplicate()
references stable.

It's a matter of discussion whether NULL or error code should be returned - the
latter might be more elegant and secure, but introducing it would mean breaking
internal API (current references). It's a cost which might be considered, if
needed.

Signed-off-by: Jan Niedziolka <j.niedziolka@xxxxxxxxxxx>
---
 drivers/gpu/drm/drm_modes.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 049d77e75ddd..fc6d974e3948 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -646,8 +646,10 @@ struct drm_display_mode *drm_cvt_mode(struct drm_device *dev, int hdisplay,
 	 * return directly
 	 */
 	drm_mode = drm_mode_create();
-	if (!drm_mode)
+	if (!drm_mode) {
+		drm_notice(dev, "Failed to create a new display mode\n");
 		return NULL;
+	}
 
 	/* the CVT default refresh rate is 60Hz */
 	if (!vrefresh)
@@ -881,8 +883,10 @@ drm_gtf_mode_complex(struct drm_device *dev, int hdisplay, int vdisplay,
 		return NULL;
 
 	drm_mode = drm_mode_create();
-	if (!drm_mode)
+	if (!drm_mode) {
+		drm_notice(dev, "Failed to create a new display mode\n");
 		return NULL;
+	}
 
 	/* 1. In order to give correct results, the number of horizontal
 	 * pixels requested is first processed to ensure that it is divisible
@@ -1458,8 +1462,10 @@ struct drm_display_mode *drm_mode_duplicate(struct drm_device *dev,
 	struct drm_display_mode *nmode;
 
 	nmode = drm_mode_create();
-	if (!nmode)
+	if (!nmode) {
+		drm_notice(dev, "Failed to create a new display mode\n");
 		return NULL;
+	}
 
 	drm_mode_copy(nmode, mode);
 
-- 
2.43.0