openwrt/target/linux/bcm27xx/patches-5.10/950-0677-drm-vc4-hdmi-Only-call-into-DRM-framework-if-registe.patch

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
@@ -1603,7 +1603,7 @@ 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;