[PATCH 02/14] drm/i915/dp: Return early if DSC not supported

[Nautiyal, Ankit K]

On 12/17/2024 4:32 PM, Jani Nikula wrote:
> On Tue, 17 Dec 2024, Jani Nikula <jani.nikula at linux.intel.com> wrote:
>> On Tue, 17 Dec 2024, Ankit Nautiyal <ankit.k.nautiyal at intel.com> wrote:
>>> Check for DSC support before computing link config with DSC.
>>> For DP MST we are already doing the same.
>>>
>>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
>>> Reviewed-by: Suraj Kandpal <suraj.kandpal at intel.com>
>>> ---
>>>   drivers/gpu/drm/i915/display/intel_dp.c | 6 +++---
>>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
>>> index 908b9887f89b..dd2da9facaad 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>>> @@ -2375,9 +2375,6 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
>>>   		 intel_dp_supports_fec(intel_dp, connector, pipe_config) &&
>>>   		 !intel_dp_is_uhbr(pipe_config));
>>>   
>>> -	if (!intel_dp_supports_dsc(intel_dp, connector, pipe_config))
>>> -		return -EINVAL;
>>> -
>>>   	if (!intel_dp_dsc_supports_format(connector, pipe_config->output_format))
>>>   		return -EINVAL;
>>>   
>>> @@ -2652,6 +2649,9 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
>>>   			    str_yes_no(ret), str_yes_no(joiner_needs_dsc),
>>>   			    str_yes_no(intel_dp->force_dsc_en));
>>>   
>>> +		if (!intel_dp_supports_dsc(intel_dp, connector, pipe_config))
>>> +			return -EINVAL;
>>> +
>> The (pre-existing) problem with this is that we debug log we fall back
>> to DSC, while we don't.
>>
>> Maybe we should do something like this instead, both in SST and MST code:
> On second thought, this can also come as a follow-up later. I don't want
> to block the series with this.


Thanks Jani for the reviews and suggestions.

I will address the debug logging issue separately as suggested.

Regards,

Ankit


>
> BR,
> Jani.
>
>
>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>> @@ -2644,6 +2644,11 @@ intel_dp_compute_link_config(struct intel_encoder *encoder,
>>   			dsc_needed = true;
>>   	}
>>   
>> +	if (dsc_needed && !intel_dp_supports_dsc(connector, pipe_config)) {
>> +		drm_dbg_kms(display->drm, "DSC required but not available.\n");
>> +		return -EINVAL;
>> +	}
>> +
>>   	if (dsc_needed) {
>>   		drm_dbg_kms(display->drm,
>>   			    "Try DSC (fallback=%s, joiner=%s, force=%s)\n",
>>
>> BR,
>> Jani.
>>
>>>   		if (!intel_dp_compute_config_limits(intel_dp, pipe_config,
>>>   						    respect_downstream_limits,
>>>   						    true,