On Thu, Sep 14, 2023 at 10:26:57PM +0300, Imre Deak wrote:
> Atm the driver supports DSC on MST links only by enabling it globally in
> the first branch device UFP's physical DPCD (vs. enabling it per-stream
> in the virtual DPCD right upstream the DPRX). This means the branch
> device will decompress any compressed stream (which it recognizes via
> MSA / SDP compression info), but it does this only for streams going to
> an SST output port. Accordingly allow DSC only for streams going to an
> SST output port of the first branch device.
>
> Signed-off-by: Imre Deak <imre.d...@intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovs...@intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_dp_mst.c | 26 +++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> index b2ac29a157fbd..f24f656d6d02a 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
> @@ -335,6 +335,27 @@ intel_dp_mst_compute_config_limits(struct intel_dp
> *intel_dp,
> limits);
> }
>
> +static bool intel_dp_mst_port_supports_dsc(struct intel_dp *intel_dp,
> + struct intel_crtc_state *crtc_state,
> + struct drm_connector_state
> *conn_state)
> +{
> + struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> + struct intel_connector *connector =
> + to_intel_connector(conn_state->connector);
> + struct intel_crtc *crtc =
> + to_intel_crtc(crtc_state->uapi.crtc);
> +
> + if (connector->port->parent != intel_dp->mst_mgr.mst_primary) {
> + drm_dbg_kms(&i915->drm,
> + "[CRTC:%d:%s] DSC only allowed on sink ports of the
> first branch device\n",
> + crtc->base.base.id, crtc->base.name);
> +
> + return false;
> + }
> +
> + return true;
> +}
> +
> static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
> struct intel_crtc_state *pipe_config,
> struct drm_connector_state *conn_state)
> @@ -378,6 +399,11 @@ static int intel_dp_mst_compute_config(struct
> intel_encoder *encoder,
> str_yes_no(ret),
> str_yes_no(intel_dp->force_dsc_en));
>
> + if (!intel_dp_mst_port_supports_dsc(intel_dp,
> + pipe_config,
> + conn_state))
> + return -EINVAL;
> +
> if (!intel_dp_mst_compute_config_limits(intel_dp,
> pipe_config,
> true,
> --
> 2.37.2
>
