Re: [PATCH 10/14] drm/i915/display/vdsc: Add ultrajoiner support with DSC

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

On 9/6/2024 10:09 PM, Ville Syrjälä wrote:
> On Fri, Sep 06, 2024 at 07:30:16PM +0300, Ville Syrjälä wrote:
>> On Fri, Sep 06, 2024 at 06:28:03PM +0530, Ankit Nautiyal wrote:
>>> From: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
>>>
>>> Add changes to DSC which are required for Ultrajoiner.
>>>
>>> v2:
>>> -Use correct helper for setting bits for bigjoiner secondary. (Ankit)
>>> -Use enum for joiner pipe count instead magic numbers. (Suraj)
>>> -Use primary/secondary instead of master/slave. (Suraj)
>>>
>>> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
>>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
>>> ---
>>>   drivers/gpu/drm/i915/display/intel_vdsc.c | 26 +++++++++++++++++++++--
>>>   1 file changed, 24 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
>>> index 8158e3702ed5..66e810c8de68 100644
>>> --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
>>> +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
>>> @@ -379,9 +379,11 @@ static int intel_dsc_get_vdsc_per_pipe(const struct intel_crtc_state *crtc_state
>>>   int intel_dsc_get_num_vdsc_instances(const struct intel_crtc_state *crtc_state)
>>>   {
>>>   	int num_vdsc_instances = intel_dsc_get_vdsc_per_pipe(crtc_state);
>>> +	int joined_pipes = intel_joiner_num_pipes(crtc_state);
>>>   
>>> -	if (crtc_state->joiner_pipes)
>>> -		num_vdsc_instances *= 2;
>>> +	if (joined_pipes == INTEL_BIG_JOINER_PIPES ||
>>> +	    joined_pipes == INTEL_ULTRA_JOINER_PIPES)
>>> +		num_vdsc_instances *= joined_pipes;
>>>   
>>>   	return num_vdsc_instances;
>>>   }
>>> @@ -751,6 +753,14 @@ void intel_uncompressed_joiner_enable(const struct intel_crtc_state *crtc_state)
>>>   	}
>>>   }
>>>   
>>> +static bool intel_crtc_ultrajoiner_enable_needed(const struct intel_crtc_state *crtc_state)
>>> +{
>>> +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>>> +
>>> +	return intel_joiner_num_pipes(crtc_state) == INTEL_ULTRA_JOINER_PIPES &&
>>> +	       crtc->pipe != PIPE_D;
>>> +}
>>> +
>>>   void intel_dsc_enable(const struct intel_crtc_state *crtc_state)
>>>   {
>>>   	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
>>> @@ -770,7 +780,19 @@ void intel_dsc_enable(const struct intel_crtc_state *crtc_state)
>>>   		dss_ctl1_val |= JOINER_ENABLE;
>>>   	}
>>>   	if (crtc_state->joiner_pipes) {
>>> +		/*
>>> +		 * This bit doesn't seem to follow primary/secondary logic or
>>> +		 * any other logic, so lets just add helper function to
>>> +		 * at least hide this hassle..
>>> +		 */
>>> +		if (intel_crtc_ultrajoiner_enable_needed(crtc_state))
>> What is this crazyness? This would throw a big wrench into
>> the works, eg. the ultrajoiner readout would not work as intended.
> Hmm. I do see a note to this effect in bspec. But that doesn't make
> any real sense. I would expect that we either enable this for
> everything, or only for pipes A+C (the bigjoiner primaries).
> The latter would seem sensible, but it would also mean that
> we need to rethink the readout as well.

Yes as per bspec : The ULTRA_JOINER_ENABLE bit will be set for Pipe A, 
Pipe B and Pipe C only.

Are you suggesting to write this for D as well? or just for A and C?

Also PRIMARY_ULTRA_JOINER_ENABLE is to be set for A. For other pipes 
this bit will be reset.

Though only C is ultrajoiner secondary pipe, but since for other pipes 
this bit is reset, how to make that distinction between C and others.

I mean readout will tell ultrajoiner primary as A and ultrajoiner 
secondary as B,C,D as bit is reset for all three.

Currently we have secondary ultrajoiner pipes reading 0xE.

Regards,

Ankit

>>> +			dss_ctl1_val |= ULTRA_JOINER_ENABLE;
>>> +
>>> +		if (intel_crtc_is_ultrajoiner_primary(crtc_state))
>>> +			dss_ctl1_val |= PRIMARY_ULTRA_JOINER_ENABLE;
>>> +
>>>   		dss_ctl1_val |= BIG_JOINER_ENABLE;
>>> +
>>>   		if (intel_crtc_is_bigjoiner_primary(crtc_state))
>>>   			dss_ctl1_val |= PRIMARY_BIG_JOINER_ENABLE;
>>>   	}
>>> -- 
>>> 2.45.2
>> -- 
>> Ville Syrjälä
>> Intel