[Intel-gfx] [PATCH 08/11] drm/i915/display/vrr: Send VRR push to flip the frame

[Jani Nikula]

On Thu, 22 Oct 2020, Manasi Navare <manasi.d.navare at intel.com> wrote:
> VRR achieves vblank stretching using the HW PUSH functionality.
> So once the VRR is enabled during modeset then for each flip
> request from userspace, in the atomic tail pipe_update_end()
> we need to set the VRR push bit in HW for it to terminate
> the vblank at configured flipline or anytime after flipline
> or latest at the Vmax.
>
> The HW clears the PUSH bit after the double buffer updates
> are completed.
>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_sprite.c |  5 +++++
>  drivers/gpu/drm/i915/display/intel_vrr.c    | 17 +++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_vrr.h    |  1 +
>  3 files changed, 23 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c b/drivers/gpu/drm/i915/display/intel_sprite.c
> index b6deeb338477..cb10fe462f06 100644
> --- a/drivers/gpu/drm/i915/display/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/display/intel_sprite.c
> @@ -49,6 +49,7 @@
>  #include "intel_psr.h"
>  #include "intel_dsi.h"
>  #include "intel_sprite.h"
> +#include "intel_vrr.h"
>  
>  int intel_usecs_to_scanlines(const struct drm_display_mode *adjusted_mode,
>  			     int usecs)
> @@ -217,6 +218,10 @@ void intel_pipe_update_end(struct intel_crtc_state *new_crtc_state)
>  	    intel_crtc_has_type(new_crtc_state, INTEL_OUTPUT_DSI))
>  		icl_dsi_frame_update(new_crtc_state);
>  
> +	/* Send VRR Push to terminate Vblank */
> +	if (new_crtc_state->vrr.enable)
> +		intel_vrr_send_push(new_crtc_state);
> +

Maybe move the vrr.enable check to the function?

>  	/* We're still in the vblank-evade critical section, this can't race.
>  	 * Would be slightly nice to just grab the vblank count and arm the
>  	 * event outside of the critical section - the spinlock might spin for a
> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
> index 7f1353bac583..ec1ce88e869c 100644
> --- a/drivers/gpu/drm/i915/display/intel_vrr.c
> +++ b/drivers/gpu/drm/i915/display/intel_vrr.c
> @@ -102,3 +102,20 @@ void intel_vrr_enable(struct intel_encoder *encoder,
>  		trans_push);
>  }
>  
> +void intel_vrr_send_push(const struct intel_crtc_state *crtc_state)
> +{
> +	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
> +	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> +	enum pipe pipe = crtc->pipe;
> +	u32 trans_push;
> +
> +	trans_push = intel_de_read(dev_priv, TRANS_PUSH(pipe));
> +	WARN_ON(!(trans_push & TRANS_PUSH_EN));

drm_WARN_ON, and perhaps move this below the register rmw. It doesn't
change the flow anyway.

> +
> +	trans_push |= TRANS_PUSH_SEND;
> +	intel_de_write(dev_priv, TRANS_PUSH(pipe), trans_push);
> +
> +	drm_dbg(&dev_priv->drm, "Sending VRR Push on Pipe (%c)\n",
> +		pipe_name(pipe));

drm_dbg_kms

> +}
> +
> diff --git a/drivers/gpu/drm/i915/display/intel_vrr.h b/drivers/gpu/drm/i915/display/intel_vrr.h
> index 05d982d6fbae..a6b78e1676cb 100644
> --- a/drivers/gpu/drm/i915/display/intel_vrr.h
> +++ b/drivers/gpu/drm/i915/display/intel_vrr.h
> @@ -19,5 +19,6 @@ void intel_vrr_compute_config(struct intel_dp *intel_dp,
>  			      struct intel_crtc_state *crtc_state);
>  void intel_vrr_enable(struct intel_encoder *encoder,
>  		      const struct intel_crtc_state *crtc_state);
> +void intel_vrr_send_push(const struct intel_crtc_state *crtc_state);
>  
>  #endif /* __INTEL_VRR_H__ */

-- 
Jani Nikula, Intel Open Source Graphics Center