[PATCH] drm/i915/dp: Correct max compressed bpp bounds by using link bpp

[Jani Nikula]

On Thu, 16 Jan 2025, Rodrigo Vivi <rodrigo.vivi at intel.com> wrote:
> On Thu, Jan 16, 2025 at 03:24:16PM +0530, Ankit Nautiyal wrote:
>> While setting the bounds for compressed bpp we ensure that the
>> compressed bpp is less than the pipe bpp.
>> 
>> This gives an issue with 420 output format where effective link bpp is
>> half that of the pipe bpp. Therefore instead of pipe bpp use link bpp to
>> set the bounds for the compressed bpp.
>> 
>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
>> ---
>>  drivers/gpu/drm/i915/display/intel_dp.c | 10 ++++++++--
>
> patches to i915, even when they target only platforms supported by
> xe should also be sent to intel-gfx mainlinlist...

Agreed... but this one was? :)

BR,
Jani.

>
>>  1 file changed, 8 insertions(+), 2 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
>> index 1ad25c37f3c2..47fcfbcb893b 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>> @@ -2068,9 +2068,12 @@ icl_dsc_compute_link_config(struct intel_dp *intel_dp,
>>  			    int timeslots)
>>  {
>>  	int i, ret;
>> +	int link_bpp;
>> +
>> +	link_bpp = intel_dp_output_bpp(pipe_config->output_format, pipe_bpp);
>>  
>>  	/* Compressed BPP should be less than the Input DSC bpp */
>> -	dsc_max_bpp = min(dsc_max_bpp, pipe_bpp - 1);
>> +	dsc_max_bpp = min(dsc_max_bpp, link_bpp - 1);
>>  
>>  	for (i = 0; i < ARRAY_SIZE(valid_dsc_bpp); i++) {
>>  		if (valid_dsc_bpp[i] < dsc_min_bpp)
>> @@ -2113,6 +2116,7 @@ xelpd_dsc_compute_link_config(struct intel_dp *intel_dp,
>>  	u8 bppx16_incr = drm_dp_dsc_sink_bpp_incr(connector->dp.dsc_dpcd);
>>  	u16 compressed_bppx16;
>>  	u8 bppx16_step;
>> +	int link_bpp;
>>  	int ret;
>>  
>>  	if (DISPLAY_VER(display) < 14 || bppx16_incr <= 1)
>> @@ -2120,8 +2124,10 @@ xelpd_dsc_compute_link_config(struct intel_dp *intel_dp,
>>  	else
>>  		bppx16_step = 16 / bppx16_incr;
>>  
>> +	link_bpp = intel_dp_output_bpp(pipe_config->output_format, pipe_bpp);
>> +
>>  	/* Compressed BPP should be less than the Input DSC bpp */
>> -	dsc_max_bpp = min(dsc_max_bpp << 4, (pipe_bpp << 4) - bppx16_step);
>> +	dsc_max_bpp = min(dsc_max_bpp << 4, (link_bpp << 4) - bppx16_step);
>>  	dsc_min_bpp = dsc_min_bpp << 4;
>>  
>>  	for (compressed_bppx16 = dsc_max_bpp;
>> -- 
>> 2.45.2
>> 

-- 
Jani Nikula, Intel