[ Upstream commit 1b9bd09630d4db4827cc04d358a41a16a6bc2cb0 ]
We're not allowed to create new properties after device registration so for MST connectors we need to either create the max_bpc property earlier, or we reuse one we already have. Let's do the latter apporach since the corresponding SST connector already has the prop and its min/max are correct also for the MST connector.
The problem was highlighted by commit 4f5368b5541a ("drm/kms: Catch mode_object lifetime errors") which results in the following spew: [ 1330.878941] WARNING: CPU: 2 PID: 1554 at drivers/gpu/drm/drm_mode_object.c:45 __drm_mode_object_add+0xa0/0xb0 [drm] ... [ 1330.879008] Call Trace: [ 1330.879023] drm_property_create+0xba/0x180 [drm] [ 1330.879036] drm_property_create_range+0x15/0x30 [drm] [ 1330.879048] drm_connector_attach_max_bpc_property+0x62/0x80 [drm] [ 1330.879086] intel_dp_add_mst_connector+0x11f/0x140 [i915] [ 1330.879094] drm_dp_add_port.isra.20+0x20b/0x440 [drm_kms_helper] ...
Cc: stable@vger.kernel.org Cc: Lyude Paul lyude@redhat.com Cc: sunpeng.li@amd.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Sean Paul sean@poorly.run Fixes: 5ca0ef8a56b8 ("drm/i915: Add max_bpc property for DP MST") Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20190820161657.9658-1-ville.sy... Reviewed-by: José Roberto de Souza jose.souza@intel.com Reviewed-by: Lyude Paul lyude@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/i915/intel_dp_mst.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c index 8839eaea83715..d89120dcac67d 100644 --- a/drivers/gpu/drm/i915/intel_dp_mst.c +++ b/drivers/gpu/drm/i915/intel_dp_mst.c @@ -535,7 +535,15 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
intel_attach_force_audio_property(connector); intel_attach_broadcast_rgb_property(connector); - drm_connector_attach_max_bpc_property(connector, 6, 12); + + /* + * Reuse the prop from the SST connector because we're + * not allowed to create new props after device registration. + */ + connector->max_bpc_property = + intel_dp->attached_connector->base.max_bpc_property; + if (connector->max_bpc_property) + drm_connector_attach_max_bpc_property(connector, 6, 12);
return connector;