video: fbdev: fsl: Fix kernel crash when diu_ops is not implemented

commit acfc1cc13fe5bc6d7a10afa624f1e560850ddad3 upstream.

If diu_ops is not implemented on platform, kernel will access a NULL
pointer. We need to check this pointer in DIU initialization.

Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
Acked-by: Timur Tabi <timur@tabi.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/video/fsl-diu-fb.c b/drivers/video/fsl-diu-fb.c
index a16beeb..b7f6485 100644 (file)
--- a/drivers/video/fsl-diu-fb.c
+++ b/drivers/video/fsl-diu-fb.c
@@ -446,7 +446,10 @@ static enum fsl_diu_monitor_port fsl_diu_name_to_port(const char *s)
                        port = FSL_DIU_PORT_DLVDS;
        }
 
-       return diu_ops.valid_monitor_port(port);
+       if (diu_ops.valid_monitor_port)
+               port = diu_ops.valid_monitor_port(port);
+
+       return port;
 }
 
 /**
@@ -1759,6 +1762,14 @@ static int __init fsl_diu_init(void)
 #else
        monitor_port = fsl_diu_name_to_port(monitor_string);
 #endif
+
+       /*
+        * Must to verify set_pixel_clock. If not implement on platform,
+        * then that means that there is no platform support for the DIU.
+        */
+       if (!diu_ops.set_pixel_clock)
+               return -ENODEV;
+
        pr_info("Freescale Display Interface Unit (DIU) framebuffer driver\n");
 
 #ifdef CONFIG_NOT_COHERENT_CACHE