[PATCH 2/3] drm/omap: avoid aquiring mutex in atomic context

[Rob Clark]

From: Rob Clark <rob at ti.com>

omap_gem_roll() could be called by fbcon in atomic context.  Avoid
aquiring mutex, or calling tiler_pin() (which itself is not safe
for atomic context) in these cases.

Signed-off-by: Rob Clark <rob at ti.com>
---
 drivers/staging/omapdrm/omap_gem.c |   16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/omapdrm/omap_gem.c b/drivers/staging/omapdrm/omap_gem.c
index 9684891..2bc570a 100644
--- a/drivers/staging/omapdrm/omap_gem.c
+++ b/drivers/staging/omapdrm/omap_gem.c
@@ -538,10 +538,22 @@ int omap_gem_roll(struct drm_gem_object *obj, uint32_t roll)
 		return -EINVAL;
 	}
 
-	mutex_lock(&obj->dev->struct_mutex);
-
 	omap_obj->roll = roll;
 
+	if (in_atomic()) {
+		/* this can get called from fbcon in atomic context.. so
+		 * just ignore it and wait for next time called from
+		 * interruptible context to update the PAT.. the result
+		 * may be that user sees wrap-around instead of scrolling
+		 * momentarily on the screen.  If we wanted to be fancier
+		 * we could perhaps schedule some workqueue work at this
+		 * point.
+		 */
+		return 0;
+	}
+
+	mutex_lock(&obj->dev->struct_mutex);
+
 	/* if we aren't mapped yet, we don't need to do anything */
 	if (omap_obj->block) {
 		struct page **pages;
-- 
1.7.5.4