With simplefb and vc4 both enabled, simplefb would probe first and be
fb0, displaying for a moment before vc4 probed fb1 and reconfigured
the graphics hardware so that only its fbdev worked.
Cc: javier@xxxxxxxxxxxxxxx
Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
---
Ccing Javier, since it looks like Exynos has also had this trouble,
and may want to get some compatible string in the list.
drivers/video/fbdev/simplefb.c | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index e9cf19977285..a2971aa686f5 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -512,11 +512,44 @@ static struct platform_driver simplefb_driver = {
.remove = simplefb_remove,
};
+/* Returns true if a simplefb node that's present should be ignored.
+ *
+ * The U-Boot bootloader, and possibly others, may add a simplefb
+ * device node to the existing device tree based on the video
+ * configuration initialized by the firmware. If we have a native
+ * driver for graphics, then simplefb would just be writing into
+ * memory that's no longer being scanned out.
+ */
+static bool
+simplefb_superseded(void)
+{
+ static const char *compats[] __initconst = {
+#ifdef CONFIG_DRM_VC4
+ "brcm,bcm2835-vc4",
+#endif
+ };
+ struct device_node *node;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(compats); i++) {
+ node = of_find_compatible_node(NULL, NULL, compats[i]);
+ if (node) {
+ of_node_put(node);
+ return true;
+ }
+ }
+
+ return false;
+}
+
static int __init simplefb_init(void)
{
int ret;
struct device_node *np;
+ if (simplefb_superseded())
+ return 0;
+
ret = platform_driver_register(&simplefb_driver);
if (ret)
return ret;
--
2.8.0.rc3
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