Re: [Intel-gfx] [PATCH v4 01/30] drm/i915/dp_mst: Fix race between connector registration and setup

["Lisovskiy, Stanislav" <stanislav.lisovskiy@intel.com>]

On Mon, Oct 30, 2023 at 05:58:14PM +0200, Imre Deak wrote:
> After drm_connector_init() is called the connector is visible to the
> rest of the kernel via the drm_mode_config::connector_list. Make
> sure that the DSC AUX device and capabilities are setup by that time.
> 
> Another race condition is adding the connector to the connector list
> before drm_connector_helper_add() sets the connector helper functions.
> That's an unrelated issue, for which the fix is for a follow-up. One
> solution would be adding the connector to the connector list only
> during its registration in drm_connector_register().

Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

> 
> Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Fixes: 808b43fa7e56 ("drm/i915/dp_mst: Set connector DSC capabilities and decompression AUX")
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp_mst.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index 7b4628f4f1240..851b312bd8449 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -1161,6 +1161,14 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
>  	intel_connector->port = port;
>  	drm_dp_mst_get_port_malloc(port);
>  
> +	/*
> +	 * TODO: set the AUX for the actual MST port decompressing the stream.
> +	 * At the moment the driver only supports enabling this globally in the
> +	 * first downstream MST branch, via intel_dp's (root port) AUX.
> +	 */
> +	intel_connector->dp.dsc_decompression_aux = &intel_dp->aux;
> +	intel_dp_mst_read_decompression_port_dsc_caps(intel_dp, intel_connector);
> +
>  	connector = &intel_connector->base;
>  	ret = drm_connector_init(dev, connector, &intel_dp_mst_connector_funcs,
>  				 DRM_MODE_CONNECTOR_DisplayPort);
> @@ -1172,14 +1180,6 @@ static struct drm_connector *intel_dp_add_mst_connector(struct drm_dp_mst_topolo
>  
>  	drm_connector_helper_add(connector, &intel_dp_mst_connector_helper_funcs);
>  
> -	/*
> -	 * TODO: set the AUX for the actual MST port decompressing the stream.
> -	 * At the moment the driver only supports enabling this globally in the
> -	 * first downstream MST branch, via intel_dp's (root port) AUX.
> -	 */
> -	intel_connector->dp.dsc_decompression_aux = &intel_dp->aux;
> -	intel_dp_mst_read_decompression_port_dsc_caps(intel_dp, intel_connector);
> -
>  	for_each_pipe(dev_priv, pipe) {
>  		struct drm_encoder *enc =
>  			&intel_dp->mst_encoders[pipe]->base.base;
> -- 
> 2.39.2
>