[PATCH] drm/bridge/synopsys: dsi: Don't blindly call post_disable

[Matt Redfearn]

The DRM documentation states that post_disable is an optional callback.
As such an implementing device may not populate it. To avoid panicing
the kernel by calling a NULL function pointer, we should NULL check it
before blindy calling it.

Signed-off-by: Matt Redfearn <matt.redfearn at thinci.com>

---

 drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
index 38e88071363..0ee440216b8 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
@@ -805,7 +805,8 @@ static void dw_mipi_dsi_bridge_post_disable(struct drm_bridge *bridge)
 	 * This needs to be fixed in the drm_bridge framework and the API
 	 * needs to be updated to manage our own call chains...
 	 */
-	dsi->panel_bridge->funcs->post_disable(dsi->panel_bridge);
+	if (dsi->panel_bridge->funcs->post_disable)
+		dsi->panel_bridge->funcs->post_disable(dsi->panel_bridge);
 
 	if (dsi->slave) {
 		dw_mipi_dsi_disable(dsi->slave);
-- 
2.17.1