[PATCHv2,1/5] drm_dp_cec: check that aux has a transfer function

Commit Message

Hans Verkuil Aug. 27, 2018, 7:58 a.m. UTC

From: Hans Verkuil <[e-mail]>

If aux->transfer == NULL, then just return without doing
anything. In that case the function is likely called for
a non-(e)DP connector.

This never happened for the i915 driver, but the nouveau and amdgpu
drivers need this check.

The alternative would be to add this check in those drivers before
every drm_dp_cec call, but it makes sense to check it in the
drm_dp_cec functions to prevent a kernel oops.

Signed-off-by: Hans Verkuil <[e-mail]>
Reviewed-by: Lyude Paul <[e-mail]>
Acked-by: Alex Deucher <[e-mail]>
---
 drivers/gpu/drm/drm_dp_cec.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

Patch

diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c
index 988513346e9c..1407b13a8d5d 100644
--- a/drivers/gpu/drm/drm_dp_cec.c
+++ b/drivers/gpu/drm/drm_dp_cec.c
@@ -238,6 +238,10 @@  void drm_dp_cec_irq(struct drm_dp_aux *aux)
 	u8 cec_irq;
 	int ret;
 
+	/* No transfer function was set, so not a DP connector */
+	if (!aux->transfer)
+		return;
+
 	mutex_lock(&aux->cec.lock);
 	if (!aux->cec.adap)
 		goto unlock;
@@ -293,6 +297,10 @@  void drm_dp_cec_set_edid(struct drm_dp_aux *aux, const struct edid *edid)
 	unsigned int num_las = 1;
 	u8 cap;
 
+	/* No transfer function was set, so not a DP connector */
+	if (!aux->transfer)
+		return;
+
 #ifndef CONFIG_MEDIA_CEC_RC
 	/*
 	 * CEC_CAP_RC is part of CEC_CAP_DEFAULTS, but it is stripped by
@@ -361,6 +369,10 @@  EXPORT_SYMBOL(drm_dp_cec_set_edid);
  */
 void drm_dp_cec_unset_edid(struct drm_dp_aux *aux)
 {
+	/* No transfer function was set, so not a DP connector */
+	if (!aux->transfer)
+		return;
+
 	cancel_delayed_work_sync(&aux->cec.unregister_work);
 
 	mutex_lock(&aux->cec.lock);
@@ -404,6 +416,8 @@  void drm_dp_cec_register_connector(struct drm_dp_aux *aux, const char *name,
 				   struct device *parent)
 {
 	WARN_ON(aux->cec.adap);
+	if (WARN_ON(!aux->transfer))
+		return;
 	aux->cec.name = name;
 	aux->cec.parent = parent;
 	INIT_DELAYED_WORK(&aux->cec.unregister_work,