CEC adapter functions are protected by drm_dev_enter() / _exit(), so it
is safe to keep CEC registered until DRM device is being torn down. Drop
custom CEC unsregistration code and rely on the DRM core to unregister
CEC adapter.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
drivers/gpu/drm/vc4/vc4_hdmi.c | 53 ++++++------------------------------------
1 file changed, 7 insertions(+), 46 deletions(-)
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 3086c2ad3bb2e8fafdc1f37ba985aa5785d49f9a..7b39000369e50f5368384575aa81919df5a7133c 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -2752,13 +2752,6 @@ static const struct cec_adap_ops vc4_hdmi_cec_adap_ops = {
.adap_transmit = vc4_hdmi_cec_adap_transmit,
};
-static void vc4_hdmi_cec_release(void *ptr)
-{
- struct drm_connector *connector = ptr;
-
- drm_connector_cec_unregister(connector);
-}
-
static int vc4_hdmi_cec_init(struct drm_connector *connector)
{
struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
@@ -2796,51 +2789,19 @@ static int vc4_hdmi_cec_register(struct vc4_hdmi *vc4_hdmi)
{
struct platform_device *pdev = vc4_hdmi->pdev;
struct device *dev = &pdev->dev;
- int ret;
if (!of_property_present(dev->of_node, "interrupts")) {
dev_warn(dev, "'interrupts' DT property is missing, no CEC\n");
return 0;
}
- ret = drm_connector_hdmi_cec_adapter_register(&vc4_hdmi->connector,
- &vc4_hdmi_cec_adap_ops,
- vc4_hdmi->variant->card_name,
- 1,
- vc4_hdmi_cec_init,
- NULL,
- &pdev->dev);
- if (ret < 0)
- return ret;
-
- /*
- * NOTE: Strictly speaking, we should probably use a DRM-managed
- * registration there to avoid removing the CEC adapter by the
- * time the DRM driver doesn't have any user anymore.
- *
- * However, the CEC framework already cleans up the CEC adapter
- * only when the last user has closed its file descriptor, so we
- * don't need to handle it in DRM.
- *
- * By the time the device-managed hook is executed, we will give
- * up our reference to the CEC adapter and therefore don't
- * really care when it's actually freed.
- *
- * There's still a problematic sequence: if we unregister our
- * CEC adapter, but the userspace keeps a handle on the CEC
- * adapter but not the DRM device for some reason. In such a
- * case, our vc4_hdmi structure will be freed, but the
- * cec_adapter structure will have a dangling pointer to what
- * used to be our HDMI controller. If we get a CEC call at that
- * moment, we could end up with a use-after-free. Fortunately,
- * the CEC framework already handles this too, by calling
- * cec_is_registered() in cec_ioctl() and cec_poll().
- */
- ret = devm_add_action_or_reset(dev, vc4_hdmi_cec_release, vc4_hdmi);
- if (ret)
- return ret;
-
- return 0;
+ return drm_connector_hdmi_cec_adapter_register(&vc4_hdmi->connector,
+ &vc4_hdmi_cec_adap_ops,
+ vc4_hdmi->variant->card_name,
+ 1,
+ vc4_hdmi_cec_init,
+ NULL,
+ &pdev->dev);
}
#else
static int vc4_hdmi_cec_register(struct vc4_hdmi *vc4_hdmi)
--
2.39.5
