OMAPDSS: Fix crash with DT boot

When booting with DT, there's a crash when omapfb is probed. This is
caused by the fact that omapdss+DT is not yet supported, and thus
omapdss is not probed at all. On the other hand, omapfb is always
probed. When omapfb tries to use omapdss, there's a NULL pointer
dereference crash. The same error should most likely happen with omapdrm
and omap_vout also.

To fix this, add an "initialized" state to omapdss. When omapdss has
been probed, it's marked as initialized. omapfb, omapdrm and omap_vout
check this state when they are probed to see that omapdss is actually
there.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>

2 files changed, 22 insertions, 1 deletions

diff --git a/drivers/video/omap2/dss/core.c b/drivers/video/omap2/dss/core.c
index f8779d4750ba..f49ddb9e7c82 100644
--- a/drivers/video/omap2/dss/core.c
+++ b/drivers/video/omap2/dss/core.c
@@ -53,6 +53,8 @@ static char *def_disp_name;
 module_param_named(def_disp, def_disp_name, charp, 0);
 MODULE_PARM_DESC(def_disp, "default display name");
 
+static bool dss_initialized;
+
 const char *omapdss_get_default_display_name(void)
 {
         return core.default_display_name;
@@ -66,6 +68,12 @@ enum omapdss_version omapdss_get_version(void)
 }
 EXPORT_SYMBOL(omapdss_get_version);
 
+bool omapdss_is_initialized(void)
+{
+        return dss_initialized;
+}
+EXPORT_SYMBOL(omapdss_is_initialized);
+
 struct platform_device *dss_get_core_pdev(void)
 {
         return core.pdev;
@@ -606,6 +614,8 @@ static int __init omap_dss_init(void)
                 return r;
         }
 
+        dss_initialized = true;
+
         return 0;
 }
 
@@ -636,7 +646,15 @@ static int __init omap_dss_init(void)
 
 static int __init omap_dss_init2(void)
 {
-        return omap_dss_register_drivers();
+        int r;
+
+        r = omap_dss_register_drivers();
+        if (r)
+                return r;
+
+        dss_initialized = true;
+
+        return 0;
 }
 
 core_initcall(omap_dss_init);
diff --git a/drivers/video/omap2/omapfb/omapfb-main.c b/drivers/video/omap2/omapfb/omapfb-main.c
index 717f13a93351..bb5f9fee3659 100644
--- a/drivers/video/omap2/omapfb/omapfb-main.c
+++ b/drivers/video/omap2/omapfb/omapfb-main.c
@@ -2416,6 +2416,9 @@ static int __init omapfb_probe(struct platform_device *pdev)
 
         DBG("omapfb_probe\n");
 
+        if (omapdss_is_initialized() == false)
+                return -EPROBE_DEFER;
+
         if (pdev->num_resources != 0) {
                 dev_err(&pdev->dev, "probed for an unknown device\n");
                 r = -ENODEV;