Re: [PATCH 02/19] drm/i915/overlay: Track current frontbuffer_bits

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 18 Feb 2026, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Store the current frontbuffer_bits in the overlay data. The
> main benefit here is that we get rid of the 'crtc->pipe'
> usage from intel_overlay_flip_prepare() which will have to
> move to the i915 side of the parent vs. display driver split.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_overlay.c | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c b/drivers/gpu/drm/i915/display/intel_overlay.c
> index 33a38d116c90..dd04e75fe3a7 100644
> --- a/drivers/gpu/drm/i915/display/intel_overlay.c
> +++ b/drivers/gpu/drm/i915/display/intel_overlay.c
> @@ -205,6 +205,7 @@ struct intel_overlay {
>  	struct drm_i915_gem_object *reg_bo;
>  	struct overlay_registers __iomem *regs;
>  	u32 flip_addr;
> +	u32 frontbuffer_bits;
>  	/* flip handling */
>  	struct i915_active last_flip;
>  	void (*flip_complete)(struct intel_overlay *ovl);
> @@ -255,7 +256,8 @@ alloc_request(struct intel_overlay *overlay, void (*fn)(struct intel_overlay *))
>  }
>  
>  /* overlay needs to be disable in OCMD reg */
> -static int intel_overlay_on(struct intel_overlay *overlay)
> +static int intel_overlay_on(struct intel_overlay *overlay,
> +			    u32 frontbuffer_bits)
>  {
>  	struct intel_display *display = overlay->display;
>  	struct i915_request *rq;
> @@ -274,6 +276,7 @@ static int intel_overlay_on(struct intel_overlay *overlay)
>  	}
>  
>  	overlay->active = true;
> +	overlay->frontbuffer_bits = frontbuffer_bits;
>  
>  	if (display->platform.i830)
>  		i830_overlay_clock_gating(display, false);
> @@ -293,7 +296,6 @@ static void intel_overlay_flip_prepare(struct intel_overlay *overlay,
>  				       struct i915_vma *vma)
>  {
>  	struct intel_display *display = overlay->display;
> -	enum pipe pipe = overlay->crtc->pipe;
>  	struct intel_frontbuffer *frontbuffer = NULL;
>  
>  	drm_WARN_ON(display->drm, overlay->old_vma);
> @@ -302,7 +304,7 @@ static void intel_overlay_flip_prepare(struct intel_overlay *overlay,
>  		frontbuffer = intel_frontbuffer_get(intel_bo_to_drm_bo(vma->obj));
>  
>  	intel_frontbuffer_track(overlay->frontbuffer, frontbuffer,
> -				INTEL_FRONTBUFFER_OVERLAY(pipe));
> +				overlay->frontbuffer_bits);
>  
>  	if (overlay->frontbuffer)
>  		intel_frontbuffer_put(overlay->frontbuffer);
> @@ -364,7 +366,7 @@ static void intel_overlay_release_old_vma(struct intel_overlay *overlay)
>  	if (drm_WARN_ON(display->drm, !vma))
>  		return;
>  
> -	intel_frontbuffer_flip(display, INTEL_FRONTBUFFER_OVERLAY(overlay->crtc->pipe));
> +	intel_frontbuffer_flip(display, overlay->frontbuffer_bits);
>  
>  	i915_vma_unpin(vma);
>  	i915_vma_put(vma);
> @@ -382,9 +384,8 @@ static void intel_overlay_off_tail(struct intel_overlay *overlay)
>  
>  	intel_overlay_release_old_vma(overlay);
>  
> -	overlay->crtc->overlay = NULL;
> -	overlay->crtc = NULL;

The movement of these to intel_overlay_switch_off() seems like an
unrelated change. Maybe mention in the commit message at a minimum.

BR,
Jani.

>  	overlay->active = false;
> +	overlay->frontbuffer_bits = 0;
>  
>  	if (display->platform.i830)
>  		i830_overlay_clock_gating(display, true);
> @@ -506,6 +507,7 @@ void intel_overlay_reset(struct intel_display *display)
>  	overlay->old_yscale = 0;
>  	overlay->crtc = NULL;
>  	overlay->active = false;
> +	overlay->frontbuffer_bits = 0;
>  }
>  
>  static int packed_depth_bytes(u32 format)
> @@ -836,7 +838,7 @@ static int intel_overlay_do_put_image(struct intel_overlay *overlay,
>  			OCONF_PIPE_A : OCONF_PIPE_B;
>  		iowrite32(oconfig, &regs->OCONFIG);
>  
> -		ret = intel_overlay_on(overlay);
> +		ret = intel_overlay_on(overlay, INTEL_FRONTBUFFER_OVERLAY(pipe));
>  		if (ret != 0)
>  			goto out_unpin;
>  	}
> @@ -924,6 +926,9 @@ int intel_overlay_switch_off(struct intel_overlay *overlay)
>  
>  	iowrite32(0, &overlay->regs->OCMD);
>  
> +	overlay->crtc->overlay = NULL;
> +	overlay->crtc = NULL;
> +
>  	return intel_overlay_off(overlay);
>  }

-- 
Jani Nikula, Intel