Re: [PATCH v8 1/3] gpu: drm: separate panel orientation property creating and value setting

On Tue, Feb 15, 2022 at 9:17 AM Gabriel Krisman Bertazi krisman@collabora.com wrote:

Hsin-Yi Wang hsinyi@chromium.org writes:

...

drm_dev_register() sets connector->registration_state to DRM_CONNECTOR_REGISTERED and dev->registered to true. If drm_connector_set_panel_orientation() is first called after drm_dev_register(), it will fail several checks and results in following warning.

Hi,

I stumbled upon this when investigating the same WARN_ON on amdgpu. Thanks for the patch :)

...

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c index a50c82bc2b2fec..572ead7ac10690 100644 --- a/drivers/gpu/drm/drm_connector.c +++ b/drivers/gpu/drm/drm_connector.c @@ -1252,7 +1252,7 @@ static const struct drm_prop_enum_list dp_colorspaces[] = {

• INPUT_PROP_DIRECT) will still map 1:1 to the actual LCD panel
• coordinates, so if userspace rotates the picture to adjust for
• the orientation it must also apply the same transformation to the

• • touchscreen input coordinates. This property is initialized by calling

• • touchscreen input coordinates. This property value is set by calling
  • drm_connector_set_panel_orientation() or
  • drm_connector_set_panel_orientation_with_quirk()

@@ -2341,8 +2341,8 @@ EXPORT_SYMBOL(drm_connector_set_vrr_capable_property);

• @connector: connector for which to set the panel-orientation property.
• @panel_orientation: drm_panel_orientation value to set

• • This function sets the connector's panel_orientation and attaches
• • a "panel orientation" property to the connector.

• • This function sets the connector's panel_orientation value. If the property
• • doesn't exist, it will try to create one.
  • Calling this function on a connector where the panel_orientation has
  • already been set is a no-op (e.g. the orientation has been overridden with

@@ -2373,19 +2373,12 @@ int drm_connector_set_panel_orientation( info->panel_orientation = panel_orientation;

  prop = dev->mode_config.panel_orientation_property;

• if (!prop) {
  

•         prop = drm_property_create_enum(dev, DRM_MODE_PROP_IMMUTABLE,
  

•                         "panel orientation",
  

•                         drm_panel_orientation_enum_list,
  

•                         ARRAY_SIZE(drm_panel_orientation_enum_list));
  

•         if (!prop)
  

•                 return -ENOMEM;
  

•         dev->mode_config.panel_orientation_property = prop;
  

• }
  

• if (!prop &&
  

•     drm_connector_init_panel_orientation_property(connector) < 0)
  

•         return -ENOMEM;
  
  

In the case where the property has not been created beforehand, you forgot to reinitialize prop here, after calling drm_connector_init_panel_orientation_property(). This means

hi Gabriel,

drm_connector_init_panel_orientation_property() will create prop if it's null. If prop fails to be created there, it will return -ENOMEM.

drm_object_property_set_value() will be called with a NULL second argument and Oops the kernel.

...

• drm_object_attach_property(&connector->base, prop,
  

•                            info->panel_orientation);
  

• drm_object_property_set_value(&connector->base, prop,
  

•                               info->panel_orientation);
  

-- Gabriel Krisman Bertazi