On Mon, Feb 03, 2025 at 06:08:34PM +0200, Jani Nikula wrote:
> Drop the UHBR limitation from DP SST DSC, and handle SST DSC bandwidth
> computation for UHBR using intel_dp_mtp_tu_compute_config().
>
> Cc: Imre Deak <imre.deak@xxxxxxxxx>
> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx>
With the DPT bpp and bpp_step fixes on the list, this seems to work on a
DP2.0 dock on (SST) UHBR link/DSC mode.
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 35 +++++++++++++++++++------
> 1 file changed, 27 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index cc6aba353c11..eb8f6806166c 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1958,15 +1958,37 @@ static int dsc_compute_link_config(struct intel_dp *intel_dp,
> for (lane_count = limits->min_lane_count;
> lane_count <= limits->max_lane_count;
> lane_count <<= 1) {
> - if (!is_bw_sufficient_for_dsc_config(dsc_bpp_x16, link_rate,
> - lane_count, adjusted_mode->clock,
> - pipe_config->output_format,
> - timeslots))
> - continue;
>
> + /*
> + * FIXME: intel_dp_mtp_tu_compute_config() requires
> + * ->lane_count and ->port_clock set before we know
> + * they'll work. If we end up failing altogether,
> + * they'll remain in crtc state. This shouldn't matter,
> + * as we'd then bail out from compute config, but it's
> + * just ugly.
> + */
> pipe_config->lane_count = lane_count;
> pipe_config->port_clock = link_rate;
>
> + if (drm_dp_is_uhbr_rate(link_rate)) {
> + int ret;
> +
> + ret = intel_dp_mtp_tu_compute_config(intel_dp,
> + pipe_config,
> + conn_state,
> + dsc_bpp_x16,
> + dsc_bpp_x16,
> + 0, true);
> + if (ret)
> + continue;
> + } else {
> + if (!is_bw_sufficient_for_dsc_config(dsc_bpp_x16, link_rate,
> + lane_count, adjusted_mode->clock,
> + pipe_config->output_format,
> + timeslots))
> + continue;
> + }
> +
> return 0;
> }
> }
> @@ -2493,9 +2515,6 @@ intel_dp_compute_config_limits(struct intel_dp *intel_dp,
> limits->min_rate = intel_dp_min_link_rate(intel_dp);
> limits->max_rate = intel_dp_max_link_rate(intel_dp);
>
> - /* FIXME 128b/132b SST+DSC support missing */
> - if (!is_mst && dsc)
> - limits->max_rate = min(limits->max_rate, 810000);
> limits->min_rate = min(limits->min_rate, limits->max_rate);
>
> limits->min_lane_count = intel_dp_min_lane_count(intel_dp);
> --
> 2.39.5
>
