[PATCH 18/20] drm/i915/vrr: Use fixed timings for platforms that support VRR

[Nautiyal, Ankit K]

On 2/26/2025 8:41 PM, Ville Syrjälä wrote:
> On Mon, Feb 24, 2025 at 11:47:15AM +0530, Ankit Nautiyal wrote:
>> For fixed refresh rate use fixed timings for all platforms that support
>> VRR. For this add checks to avoid computing and reading VRR for
>> platforms that do not support VRR.
>> For platforms that do support VRR, readback vrr timings whether or not
>> VRR_CTL_FLIP_LINE_EN is set in VRR_CTL or not.
>>
>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
>> ---
>>   drivers/gpu/drm/i915/display/intel_vrr.c | 43 ++++++++++++------------
>>   1 file changed, 22 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
>> index 551dcc16f0d4..975fed9930c1 100644
>> --- a/drivers/gpu/drm/i915/display/intel_vrr.c
>> +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
>> @@ -344,6 +344,9 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
>>   	struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
>>   	int vmin = 0, vmax = 0;
>>   
>> +	if (!HAS_VRR(display))
>> +		return;
>> +
>>   	if (adjusted_mode->flags & DRM_MODE_FLAG_INTERLACE)
>>   		return;
>>   
>> @@ -358,9 +361,6 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
>>   
>>   	vmin = intel_vrr_compute_vmin(crtc_state);
>>   
>> -	if (vmin >= vmax)
>> -		return;
>> -
>>   	crtc_state->vrr.vmin = vmin;
>>   	crtc_state->vrr.vmax = vmax;
> I think your earlier pathc left vmax==0 here for the !in_range so
> this looks a bit wrong. But if you change the earlier patch like I
> suggested to set vmax=vmin then this would be fine.

Right, will set the vmax=vmin, as discussed in the earlier patch.


>
>>   
>> @@ -373,7 +373,7 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
>>   	 */
>>   	crtc_state->vrr.vmin -= intel_vrr_flipline_offset(display);
>>   
>> -	if (crtc_state->uapi.vrr_enabled)
>> +	if (crtc_state->uapi.vrr_enabled && vmin < vmax)
>>   		intel_vrr_compute_vrr_timings(crtc_state);
>>   	else if (is_cmrr_frac_required(crtc_state) && is_edp)
>>   		intel_vrr_compute_cmrr_timings(crtc_state);
>> @@ -640,6 +640,9 @@ void intel_vrr_get_config(struct intel_crtc_state *crtc_state)
>>   	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
>>   	u32 trans_vrr_ctl, trans_vrr_vsync;
>>   
>> +	if (!HAS_VRR(display))
>> +		return;
> I think the caller is already checking that. But I suppose we could
> move the checks into the VRR code.
>
>> +
>>   	trans_vrr_ctl = intel_de_read(display,
>>   				      TRANS_VRR_CTL(display, cpu_transcoder));
>>   
>> @@ -663,23 +666,21 @@ void intel_vrr_get_config(struct intel_crtc_state *crtc_state)
>>   			crtc_state->vrr.pipeline_full =
>>   				REG_FIELD_GET(VRR_CTL_PIPELINE_FULL_MASK, trans_vrr_ctl);
>>   
>> -	if (trans_vrr_ctl & VRR_CTL_FLIP_LINE_EN) {
>> -		crtc_state->vrr.flipline = intel_de_read(display,
>> -							 TRANS_VRR_FLIPLINE(display, cpu_transcoder)) + 1;
>> -		crtc_state->vrr.vmax = intel_de_read(display,
>> -						     TRANS_VRR_VMAX(display, cpu_transcoder)) + 1;
>> -		crtc_state->vrr.vmin = intel_de_read(display,
>> -						     TRANS_VRR_VMIN(display, cpu_transcoder)) + 1;
>> -
>> -		if (HAS_AS_SDP(display)) {
>> -			trans_vrr_vsync =
>> -				intel_de_read(display,
>> -					      TRANS_VRR_VSYNC(display, cpu_transcoder));
>> -			crtc_state->vrr.vsync_start =
>> -				REG_FIELD_GET(VRR_VSYNC_START_MASK, trans_vrr_vsync);
>> -			crtc_state->vrr.vsync_end =
>> -				REG_FIELD_GET(VRR_VSYNC_END_MASK, trans_vrr_vsync);
>> -		}
> I think you want to keep the VRR_CTL_FLIP_LINE_EN check around the
> TRANS_VRR_FLIPLINE read at least, because we want the state checker
> to catch any misprogrammng of VRR_CTL_FLIP_LINE_EN.

Alright, will remove this change.


There is one more thing I wanted your opinion on:

For PTL+, the support for TRANS_VTOTAL.Vtotal bits is going away. I can 
skip writing it based on the intel_vrr_always_use_vrr_tg(), but how 
should I fill adjusted_mode->crtc_vtotal during readout?

Can we use vrr.vmin for that? Or should we just remove the state checker 
for crtc_vtotal for platforms where this applies?

I am intending to include this change as the last patch of the series.

Thanks again for all the reviews and suggestions.


Regards,

Ankit


>
>> +	crtc_state->vrr.flipline = intel_de_read(display,
>> +						 TRANS_VRR_FLIPLINE(display, cpu_transcoder)) + 1;
>> +	crtc_state->vrr.vmax = intel_de_read(display,
>> +					     TRANS_VRR_VMAX(display, cpu_transcoder)) + 1;
>> +	crtc_state->vrr.vmin = intel_de_read(display,
>> +					     TRANS_VRR_VMIN(display, cpu_transcoder)) + 1;
>> +
>> +	if (HAS_AS_SDP(display)) {
>> +		trans_vrr_vsync =
>> +			intel_de_read(display,
>> +				      TRANS_VRR_VSYNC(display, cpu_transcoder));
>> +		crtc_state->vrr.vsync_start =
>> +			REG_FIELD_GET(VRR_VSYNC_START_MASK, trans_vrr_vsync);
>> +		crtc_state->vrr.vsync_end =
>> +			REG_FIELD_GET(VRR_VSYNC_END_MASK, trans_vrr_vsync);
>>   	}
>>   
>>   	crtc_state->vrr.enable = trans_vrr_ctl & VRR_CTL_VRR_ENABLE &&
>> -- 
>> 2.45.2