On Fri, Jan 31, 2025 at 02:49:55PM +0200, Jani Nikula wrote:
> Add a platform independent helper for getting the supported DSC BPP step
> for the link.
>
> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_dp.c | 21 ++++++++++++++++-----
> 1 file changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index ecf192262eb9..a7a5bb2075da 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -2054,6 +2054,21 @@ static int dsc_src_max_compressed_bpp(struct intel_dp *intel_dp)
> return 27;
> }
>
> +/*
> + * Note: for pre-13 display you still need to check the validity of each step.
> + */
> +static int intel_dp_dsc_bpp_step_x16(const struct intel_connector *connector)
Nit: there was a guideline that these KMS objects should be passed around via
non-const pointers vs. state pointers which should be const if possible.
> +{
> + struct intel_display *display = to_intel_display(connector);
> + u8 incr = drm_dp_dsc_sink_bpp_incr(connector->dp.dsc_dpcd);
> +
> + if (DISPLAY_VER(display) < 14 || !incr)
> + return fxp_q4_from_int(1);
> +
> + /* fxp q4 */
> + return 16 / incr;
Nit: could've been fxp_q4_from_int(1) / incr;
Regardless of the nits, patch looks ok:
Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx>
> +}
> +
> /*
> * From a list of valid compressed bpps try different compressed bpp and find a
> * suitable link configuration that can support it.
> @@ -2110,16 +2125,12 @@ xelpd_dsc_compute_link_config(struct intel_dp *intel_dp,
> int timeslots)
> {
> struct intel_display *display = to_intel_display(intel_dp);
> - u8 bppx16_incr = drm_dp_dsc_sink_bpp_incr(connector->dp.dsc_dpcd);
> int output_bpp = intel_dp_output_bpp(pipe_config->output_format, pipe_bpp);
> u16 compressed_bppx16;
> u8 bppx16_step;
> int ret;
>
> - if (DISPLAY_VER(display) < 14 || bppx16_incr <= 1)
> - bppx16_step = 16;
> - else
> - bppx16_step = 16 / bppx16_incr;
> + bppx16_step = intel_dp_dsc_bpp_step_x16(connector);
>
> /* Compressed BPP should be less than the Input DSC bpp */
> dsc_max_bpp = min(dsc_max_bpp << 4, (output_bpp << 4) - bppx16_step);
> --
> 2.39.5
>
