drm_dp_cec: check that aux has a transfer function

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 <hans.verkuil@cisco.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180827075820.41109-2-hverkuil@xs4all.nl

diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c
index 988513346e9c484c07bfa46614ad335e89342aa6..1407b13a8d5d9ea51765bb242e4e63f2c14ce654 100644 (file)
--- 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,