Re: [PATCH 07/22] drm/i915/vrr: Prepare for fixed refresh rate timings

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

On 3/5/2025 12:19 AM, Ville Syrjälä wrote:
> On Tue, Mar 04, 2025 at 01:49:33PM +0530, Ankit Nautiyal wrote:
>> Currently we always compute the timings as if vrr is enabled.
>> With this approach the state checker becomes complicated when we
>> introduce fixed refresh rate mode with vrr timing generator.
>>
>> To avoid the complications, instead of always computing vrr timings, we
>> compute vrr timings based on uapi.vrr_enable knob.
>> So when the knob is disabled we always compute vmin=flipline=vmax.
>>
>> v2: Use actual timings without any adjustments while preparing for
>> fixed timings in compute_config. (Ville)
>> v3: Avoid setting fixed timings if !vrr_possible().
>>
>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
>> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (#v2)
>> ---
>>   drivers/gpu/drm/i915/display/intel_vrr.c | 73 ++++++++++++++++++++++++
>>   1 file changed, 73 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
>> index e0573e28014b..0e606dfe4a56 100644
>> --- a/drivers/gpu/drm/i915/display/intel_vrr.c
>> +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
>> @@ -246,6 +246,68 @@ void intel_vrr_compute_vrr_timings(struct intel_crtc_state *crtc_state)
>>   	crtc_state->mode_flags |= I915_MODE_FLAG_VRR;
>>   }
>>   
>> +/*
>> + * For fixed refresh rate mode Vmin, Vmax and Flipline all are set to
>> + * Vtotal value.
>> + */
>> +static
>> +int intel_vrr_fixed_rr_vtotal(const struct intel_crtc_state *crtc_state)
>> +{
>> +	struct intel_display *display = to_intel_display(crtc_state);
>> +	int crtc_vtotal = crtc_state->hw.adjusted_mode.crtc_vtotal;
>> +
>> +	if (DISPLAY_VER(display) >= 13)
>> +		return crtc_vtotal;
>> +	else
>> +		return crtc_vtotal -
>> +			intel_vrr_real_vblank_delay(crtc_state);
>> +}
>> +
>> +static
>> +int intel_vrr_fixed_rr_vmax(const struct intel_crtc_state *crtc_state)
>> +{
>> +	return intel_vrr_fixed_rr_vtotal(crtc_state);
>> +}
>> +
>> +static
>> +int intel_vrr_fixed_rr_vmin(const struct intel_crtc_state *crtc_state)
>> +{
>> +	struct intel_display *display = to_intel_display(crtc_state);
>> +
>> +	return intel_vrr_fixed_rr_vtotal(crtc_state) -
>> +		intel_vrr_flipline_offset(display);
>> +}
>> +
>> +static
>> +int intel_vrr_fixed_rr_flipline(const struct intel_crtc_state *crtc_state)
>> +{
>> +	return intel_vrr_fixed_rr_vtotal(crtc_state);
>> +}
>> +
>> +static
>> +void intel_vrr_set_fixed_rr_timings(const struct intel_crtc_state *crtc_state)
>> +{
>> +	struct intel_display *display = to_intel_display(crtc_state);
>> +	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
>> +
>> +	if (!intel_vrr_possible(crtc_state))
>> +		return;
>> +
>> +	intel_de_write(display, TRANS_VRR_VMIN(display, cpu_transcoder),
>> +		       intel_vrr_fixed_rr_vmin(crtc_state) - 1);
>> +	intel_de_write(display, TRANS_VRR_VMAX(display, cpu_transcoder),
>> +		       intel_vrr_fixed_rr_vmax(crtc_state) - 1);
>> +	intel_de_write(display, TRANS_VRR_FLIPLINE(display, cpu_transcoder),
>> +		       intel_vrr_fixed_rr_flipline(crtc_state) - 1);
>> +}
>> +
>> +static
>> +void intel_vrr_prepare_fixed_timings(struct intel_crtc_state *crtc_state)
>> +{
>> +	crtc_state->vrr.vmax = intel_vrr_vmin_flipline(crtc_state);
>> +	crtc_state->vrr.flipline = intel_vrr_vmin_flipline(crtc_state);
> I think it would be cleaner to just use crtc_vtotal during
> all this timing compute stuff, and move the magic vmin
> adjustment to be done after it's all done.
Alright so IIUC for fixed timings case :
crtc_state->vrr.vmax = crtc_state->hw.adjusted_mode.crtc_vtotal;
crtc_state->vrr.flipline = crtc_state->hw.adjusted_mode.crtc_vtotal;

And will move  crtc_state->vrr.vmin -= 
intel_vrr_flipline_offset(display); after all compute timings is done.


>
>> +}
>> +
>>   static
>>   int intel_vrr_compute_vmin(struct intel_crtc_state *crtc_state)
>>   {
>> @@ -325,6 +387,8 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
>>   		intel_vrr_compute_vrr_timings(crtc_state);
>>   	else if (is_cmrr_frac_required(crtc_state) && is_edp)
>>   		intel_vrr_compute_cmrr_timings(crtc_state);
>> +	else
>> +		intel_vrr_prepare_fixed_timings(crtc_state);
> The "compute" vs. "prepare" difference in terminology is a bit
> confusing.
Can change this to `intel_vrr_compute_fixed_rr_timings()`


Regards,

Ankit

>
>>   
>>   	if (HAS_AS_SDP(display)) {
>>   		crtc_state->vrr.vsync_start =
>> @@ -496,6 +560,13 @@ void intel_vrr_enable(const struct intel_crtc_state *crtc_state)
>>   	if (!crtc_state->vrr.enable)
>>   		return;
>>   
>> +	intel_de_write(display, TRANS_VRR_VMIN(display, cpu_transcoder),
>> +		       crtc_state->vrr.vmin - 1);
>> +	intel_de_write(display, TRANS_VRR_VMAX(display, cpu_transcoder),
>> +		       crtc_state->vrr.vmax - 1);
>> +	intel_de_write(display, TRANS_VRR_FLIPLINE(display, cpu_transcoder),
>> +		       crtc_state->vrr.flipline - 1);
>> +
>>   	intel_de_write(display, TRANS_PUSH(display, cpu_transcoder),
>>   		       TRANS_PUSH_EN);
>>   
>> @@ -523,6 +594,8 @@ void intel_vrr_disable(const struct intel_crtc_state *old_crtc_state)
>>   				TRANS_VRR_STATUS(display, cpu_transcoder),
>>   				VRR_STATUS_VRR_EN_LIVE, 1000);
>>   	intel_de_write(display, TRANS_PUSH(display, cpu_transcoder), 0);
>> +
>> +	intel_vrr_set_fixed_rr_timings(old_crtc_state);
>>   }
>>   
>>   static
>> -- 
>> 2.45.2