On Fri, 31 Jan 2025, Imre Deak <imre.deak@xxxxxxxxx> wrote:
> 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.
At this point, xelpd_dsc_compute_link_config() only has the const
variable available. This changes later in the series.
>
>> +{
>> + 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;
Good point, will fix.
>
> Regardless of the nits, patch looks ok:
>
> Reviewed-by: Imre Deak <imre.deak@xxxxxxxxx>
Thanks!
>
>> +}
>> +
>> /*
>> * 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
>>
--
Jani Nikula, Intel
