[PATCH 20/35] drm/i915/vrr: Avoid sending PUSH when VRR TG is used with Fixed refresh rate

[Ville Syrjälä]

On Fri, Jan 24, 2025 at 08:30:05PM +0530, Ankit Nautiyal wrote:
> As per the spec, the PUSH enable must be set if not configuring for a
> fixed refresh rate (i.e Vmin == Flipline == Vmax is not true).
> 
> v2: Use helper intel_vrr_use_push(). (Ville)
> v3: directly use the condition, instead of checking for VRR mode.
> 
> Bspec: 68925
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> Reviewed-by: Mitul Golani <mitulkumar.ajitkumar.golani at intel.com> (v1)
> ---
>  drivers/gpu/drm/i915/display/intel_vrr.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
> index 65bbe40881d6..34e44cd52353 100644
> --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> @@ -437,13 +437,18 @@ void intel_vrr_set_transcoder_timings(const struct intel_crtc_state *crtc_state)
>  			       VRR_VSYNC_START(crtc_state->vrr.vsync_start));
>  }
>  
> +static bool intel_vrr_use_push(const struct intel_crtc_state *crtc_state)
> +{
> +	return crtc_state->vrr.flipline != crtc_state->vrr.vmax;
> +}

> +
>  void intel_vrr_send_push(struct intel_dsb *dsb,
>  			 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_vrrtg_is_enabled(crtc_state))
> +	if (!intel_vrr_use_push(crtc_state))
>  		return;
>  
>  	if (dsb)
> @@ -462,7 +467,7 @@ bool intel_vrr_is_push_sent(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_vrrtg_is_enabled(crtc_state))
> +	if (!intel_vrr_use_push(crtc_state))
>  		return false;
>  
>  	return intel_de_read(display, TRANS_PUSH(display, cpu_transcoder)) & TRANS_PUSH_SEND;
> @@ -476,8 +481,9 @@ void intel_vrr_enable(const struct intel_crtc_state *crtc_state)
>  	if (!intel_vrrtg_is_enabled(crtc_state))
>  		return;
>  
> -	intel_de_write(display, TRANS_PUSH(display, cpu_transcoder),
> -		       TRANS_PUSH_EN);
> +	if (intel_vrr_use_push(crtc_state))
> +		intel_de_write(display, TRANS_PUSH(display, cpu_transcoder),
> +			       TRANS_PUSH_EN);

What I saw on TGL and ADL is that if you don't enable PUSH then nothing
works. So I think we just want to have this enabled whenever the VRR
timing generator is enabled.

>  
>  	if (crtc_state->vrr.mode == INTEL_VRRTG_MODE_CMRR) {
>  		intel_de_write(display, TRANS_VRR_CTL(display, cpu_transcoder),
> -- 
> 2.45.2

-- 
Ville Syrjälä
Intel