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

   1 From a4ea60641c2e5ac11d3472e723b33b36f16e6bcb Mon Sep 17 00:00:00 2001
   2 From: Maxime Ripard <maxime@cerno.tech>
   3 Date: Mon, 5 Jul 2021 16:15:56 +0200
   4 Subject: [PATCH] drm/vc4: hdmi: Only call into DRM framework if
   5  registered
   6
   7 Our hotplug handler will currently call the drm_kms_helper_hotplug_event
   8 every time a hotplug interrupt is called.
   9
  10 However, since the device is registered after all the drivers have
  11 finished their bind callback, we have a window between when we install
  12 our interrupt handler and when drm_dev_register() is eventually called
  13 where our handler can run and call drm_kms_helper_hotplug_event but the
  14 device hasn't been registered yet, causing a null pointer dereference.
  15
  16 Fix this by making sure we only call drm_kms_helper_hotplug_event if our
  17 device has been properly registered.
  18
  19 Fixes: f4790083c7c2 ("drm/vc4: hdmi: Rely on interrupts to handle hotplug")
  20 Signed-off-by: Maxime Ripard <maxime@cerno.tech>
  21 ---
  22  drivers/gpu/drm/vc4/vc4_hdmi.c | 2 +-
  23  1 file changed, 1 insertion(+), 1 deletion(-)
  24
  25 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
  26 +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
  27 @@ -1603,7 +1603,7 @@ static irqreturn_t vc4_hdmi_hpd_irq_thre
  28         struct vc4_hdmi *vc4_hdmi = priv;
  29         struct drm_device *dev = vc4_hdmi->connector.dev;
  30
  31 -       if (dev)
  32 +       if (dev && dev->registered)
  33                 drm_kms_helper_hotplug_event(dev);
  34
  35         return IRQ_HANDLED;