Re: [Intel-gfx] [v7 3/3] drm/i915/display/dsc: Force dsc BPP

[Jani Nikula <jani.nikula@intel.com>]

On Thu, 08 Jul 2021, Jani Nikula <jani.nikula@intel.com> wrote:
> On Thu, 08 Jul 2021, Vandita Kulkarni <vandita.kulkarni@intel.com> wrote:
>> Set DSC BPP to the value forced through
>> debugfs. It can go from bpc to bpp-1.
>>
>> Signed-off-by: Vandita Kulkarni <vandita.kulkarni@intel.com>
>> ---
>>  drivers/gpu/drm/i915/display/intel_dp.c | 17 +++++++++++++++++
>>  1 file changed, 17 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
>> index 5b52beaddada..3e50cdd7e448 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>> @@ -1240,6 +1240,23 @@ static int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
>>  	pipe_config->port_clock = intel_dp->common_rates[limits->max_clock];
>>  	pipe_config->lane_count = limits->max_lane_count;
>>  
>> +	if (intel_dp->force_dsc_en) {

Oh, this should check for intel_dp->force_dsc_bpp. We don't want to
always force the bpp when we force dsc enable.

>> +		/* As of today we support DSC for only RGB */
>> +		if (intel_dp->force_dsc_bpp >= 8 &&
>> +		    intel_dp->force_dsc_bpp < pipe_bpp) {
>> +			drm_dbg_kms(&dev_priv->drm,
>> +				    "DSC BPP forced to %d",
>> +				    intel_dp->force_dsc_bpp);
>> +			pipe_config->dsc.compressed_bpp =
>> +						intel_dp->force_dsc_bpp;
>> +		} else {
>> +			drm_dbg_kms(&dev_priv->drm,
>> +				    "Invalid DSC BPP %d",
>> +				    intel_dp->force_dsc_bpp);
>> +			return -EINVAL;
>
> I'd just let it use the normal compressed_bpp, with the debug message,
> instead of returning -EINVAL.
>
>> +		}
>> +	}
>> +
>
> This should be *after* the below blocks, because otherwise
> compressed_bpp will be overridden by the normal case, not by the force
> case!
>
> BR,
> Jani.
>
>>  	if (intel_dp_is_edp(intel_dp)) {
>>  		pipe_config->dsc.compressed_bpp =
>>  			min_t(u16, drm_edp_dsc_sink_output_bpp(intel_dp->dsc_dpcd) >> 4,

-- 
Jani Nikula, Intel Open Source Graphics Center
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