1 files changed, 35 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-5.10/950-0677-drm-vc4-hdmi-Only-call-into-DRM-framework-if-registe.patch b/target/linux/bcm27xx/patches-5.10/950-0677-drm-vc4-hdmi-Only-call-into-DRM-framework-if-registe.patch
new file mode 100644
index 0000000000..bac5466509
--- /dev/null
+++ b/target/linux/bcm27xx/patches-5.10/950-0677-drm-vc4-hdmi-Only-call-into-DRM-framework-if-registe.patch
@@ -0,0 +1,35 @@
+From a4ea60641c2e5ac11d3472e723b33b36f16e6bcb Mon Sep 17 00:00:00 2001
+From: Maxime Ripard <maxime@cerno.tech>
+Date: Mon, 5 Jul 2021 16:15:56 +0200
+Subject: [PATCH] drm/vc4: hdmi: Only call into DRM framework if
+ registered
+
+Our hotplug handler will currently call the drm_kms_helper_hotplug_event
+every time a hotplug interrupt is called.
+
+However, since the device is registered after all the drivers have
+finished their bind callback, we have a window between when we install
+our interrupt handler and when drm_dev_register() is eventually called
+where our handler can run and call drm_kms_helper_hotplug_event but the
+device hasn't been registered yet, causing a null pointer dereference.
+
+Fix this by making sure we only call drm_kms_helper_hotplug_event if our
+device has been properly registered.
+
+Fixes: f4790083c7c2 ("drm/vc4: hdmi: Rely on interrupts to handle hotplug")
+Signed-off-by: Maxime Ripard <maxime@cerno.tech>
+---
+ drivers/gpu/drm/vc4/vc4_hdmi.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
++++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
+@@ -1602,7 +1602,7 @@ static irqreturn_t vc4_hdmi_hpd_irq_thre
+ 	struct vc4_hdmi *vc4_hdmi = priv;
+ 	struct drm_device *dev = vc4_hdmi->connector.dev;
+ 
+-	if (dev)
++	if (dev && dev->registered)
+ 		drm_kms_helper_hotplug_event(dev);
+ 
+ 	return IRQ_HANDLED;