[PATCH] drm/rockchip: Skip suspend/resume if no display is attached

From: Matthias Kaehlcke
Date: Wed Aug 09 2017 - 19:08:25 EST


rockchip_drm_sys_suspend/resume() obains a struct drm_device pointer
from drvdata, the pointer is then dereferenced to obtain private data.
drvdata is set when a display is bound, on systems without a
(successfully probed) display drvdata is NULL and the PM functions
try to dereference a NULL pointer.

The suspend/resume code relies on a valid drm_device object, skip it if
the pointer is NULL.

Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
---
drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index c6b1b7f3a2a3..6228145d9496 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -275,11 +275,16 @@ static void rockchip_drm_fb_resume(struct drm_device *drm)
static int rockchip_drm_sys_suspend(struct device *dev)
{
struct drm_device *drm = dev_get_drvdata(dev);
- struct rockchip_drm_private *priv = drm->dev_private;
+ struct rockchip_drm_private *priv;
+
+ if (!drm)
+ /* no display attached */
+ return 0;

drm_kms_helper_poll_disable(drm);
rockchip_drm_fb_suspend(drm);

+ priv = drm->dev_private;
priv->state = drm_atomic_helper_suspend(drm);
if (IS_ERR(priv->state)) {
rockchip_drm_fb_resume(drm);
@@ -293,8 +298,13 @@ static int rockchip_drm_sys_suspend(struct device *dev)
static int rockchip_drm_sys_resume(struct device *dev)
{
struct drm_device *drm = dev_get_drvdata(dev);
- struct rockchip_drm_private *priv = drm->dev_private;
+ struct rockchip_drm_private *priv;
+
+ if (!drm)
+ /* no display attached */
+ return 0;

+ priv = drm->dev_private;
drm_atomic_helper_resume(drm, priv->state);
rockchip_drm_fb_resume(drm);
drm_kms_helper_poll_enable(drm);
--
2.14.0.434.g98096fd7a8-goog