On Wed, 13 Dec 2023, Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx> wrote:
> At the moment, while choosing the input bpc for DSC, we take into
> account the max_requested_bpc property. This creates a problem, if the
> max_requested_bpc is lower than the minimum bpc required by source with
> DSC.
>
> So consider max_requested_bpc if its within the limits that we can
> support with DSC.
>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 22 ++++++++++++++++++----
> 1 file changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index e8aa2f469142..0014aa5ea652 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -1638,6 +1638,16 @@ int intel_dp_dsc_max_src_input_bpc(struct drm_i915_private *i915)
> return 12;
> }
>
> +static int
> +intel_dp_dsc_limit_max_bpc(int max_requested_bpc, int src_dsc_max_bpc, int src_dsc_min_bpc)
> +{
> + /* Consider max_requested_bpc only if src can support it with DSC */
> + if (max_requested_bpc >= src_dsc_min_bpc)
> + return min(src_dsc_max_bpc, max_requested_bpc);
> +
> + return src_dsc_max_bpc;
> +}
> +
> int intel_dp_dsc_compute_max_bpp(const struct intel_connector *connector,
> u8 max_req_bpc)
> {
> @@ -1651,7 +1661,8 @@ int intel_dp_dsc_compute_max_bpp(const struct intel_connector *connector,
> if (!dsc_max_bpc)
> return dsc_max_bpc;
>
> - dsc_max_bpc = min(dsc_max_bpc, max_req_bpc);
> + dsc_max_bpc = intel_dp_dsc_limit_max_bpc(max_req_bpc, dsc_max_bpc,
> + intel_dp_dsc_min_src_input_bpc(i915));
Somehow that doesn't read so well.
I think something like this would improve clarity:
dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
dsc_max_bpc = intel_dp_dsc_max_src_input_bpc(i915);
max_req_bpc = clamp(max_req_bpc, dsc_min_bpc, dsc_max_bpc);
i.e. clamp the request to reasonable limits. That's more like regular
input checking. That should be done *everywhere* when
conn_state->max_requested_bpc is used.
Then min(dsc_max_bpc, max_req_bpc) is no longer needed because
max_req_bpc <= dsc_max_bpc is guaranteed.
IOW this becomes:
dsc_max_bpc = clamp(max_req_bpc, dsc_min_bpc, dsc_max_bpc);
BR,
Jani.
>
> num_bpc = drm_dp_dsc_sink_supported_input_bpcs(connector->dp.dsc_dpcd,
> dsc_bpc);
> @@ -2039,8 +2050,11 @@ bool is_dsc_pipe_bpp_sufficient(struct drm_i915_private *i915,
> {
> int dsc_max_bpc, dsc_min_bpc, dsc_max_pipe_bpp, dsc_min_pipe_bpp;
>
> - dsc_max_bpc = min(intel_dp_dsc_max_src_input_bpc(i915), conn_state->max_requested_bpc);
> dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
> + dsc_max_bpc = intel_dp_dsc_max_src_input_bpc(i915);
> +
> + dsc_max_bpc = intel_dp_dsc_limit_max_bpc(conn_state->max_requested_bpc,
> + dsc_max_bpc, dsc_min_bpc);
>
> dsc_max_pipe_bpp = min(dsc_max_bpc * 3, limits->pipe.max_bpp);
> dsc_min_pipe_bpp = max(dsc_min_bpc * 3, limits->pipe.min_bpp);
> @@ -2100,14 +2114,14 @@ static int intel_dp_dsc_compute_pipe_bpp(struct intel_dp *intel_dp,
> }
> }
>
> + dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
> dsc_max_bpc = intel_dp_dsc_max_src_input_bpc(i915);
> if (!dsc_max_bpc)
> return -EINVAL;
>
> - dsc_max_bpc = min(dsc_max_bpc, max_req_bpc);
> + dsc_max_bpc = intel_dp_dsc_limit_max_bpc(max_req_bpc, dsc_max_bpc, dsc_min_bpc);
> dsc_max_bpp = min(dsc_max_bpc * 3, limits->pipe.max_bpp);
>
> - dsc_min_bpc = intel_dp_dsc_min_src_input_bpc(i915);
> dsc_min_bpp = max(dsc_min_bpc * 3, limits->pipe.min_bpp);
>
> /*
--
Jani Nikula, Intel
