linux-kernel - [PATCH] drm/bridge/synopsys: dsi: Don't blindly call post

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Date:   Wed, 24 Apr 2019 14:22:00 +0000
From:   Matt Redfearn <matt.redfearn@...nci.com>
To:     Andrzej Hajda <a.hajda@...sung.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Philippe Cornu <philippe.cornu@...com>
CC:     "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        Matthew Redfearn <matthew.redfearn@...nci.com>,
        Nickey Yang <nickey.yang@...k-chips.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Archit Taneja <architt@...eaurora.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Subject: [PATCH] drm/bridge/synopsys: dsi: Don't blindly call post_disable

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@...nci.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