Re: [Intel-gfx] [PATCH 4/4] drm/i915/dp: Ignore max_requested_bpc if its too low for DSC

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 11/9/2023 12:19 PM, Kandpal, Suraj wrote:
>
>> -----Original Message-----
>> From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of Ankit
>> Nautiyal
>> Sent: Tuesday, November 7, 2023 9:48 AM
>> To: intel-gfx@lists.freedesktop.org
>> Cc: Nikula, Jani <jani.nikula@intel.com>
>> Subject: [Intel-gfx] [PATCH 4/4] drm/i915/dp: Ignore max_requested_bpc if its
>> too low for DSC
>>
>> 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@intel.com>
>> ---
>>   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 abc718f1a878..ea4c42a5705e 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>> @@ -1578,6 +1578,16 @@ u8 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)
>>   {
>> @@ -1591,7 +1601,8 @@ int intel_dp_dsc_compute_max_bpp(const struct
>> intel_connector *connector,
>>   	if (!dsc_max_bpc)
>>   		return dsc_max_bpc;
>>
>> -	dsc_max_bpc = min_t(u8, 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));
>>
>>   	num_bpc = drm_dp_dsc_sink_supported_input_bpcs(connector-
>>> dp.dsc_dpcd,
>>   						       dsc_bpc);
>> @@ -1959,8 +1970,11 @@ bool is_dsc_pipe_bpp_sufficient(struct
>> drm_i915_private *i915,  {
>>   	u8 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);
> Seems like this change could have been a part of the previous patch.

Hi Suraj,

Previous patch was only using helpers to get src_min_max dsc bpc for dp 
mst case.

Regards,

Ankit


>
> Regards,
> Suraj Kandpal
>> +
>> +	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);
>> @@ -2020,14 +2034,14 @@ 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_t(u8, 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);
>>
>>   	/*
>> --
>> 2.40.1