Re: [PATCH 08/11] drm/i915: Extract intel_plane_needs_fence()

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

On Thu, 16 Apr 2026, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Extract the naked DISPLA_VER<4 checks into a descriptive little
> helper (intel_plane_needs_fence()).

*DISPLAY_VER

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

>
> And while at it document the reason why the check is what it is.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_fb.c    | 2 +-
>  drivers/gpu/drm/i915/display/intel_plane.c | 9 +++++++++
>  drivers/gpu/drm/i915/display/intel_plane.h | 1 +
>  drivers/gpu/drm/i915/i915_fb_pin.c         | 2 +-
>  4 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_fb.c b/drivers/gpu/drm/i915/display/intel_fb.c
> index cbeb39ebdb73..1c0859d5f829 100644
> --- a/drivers/gpu/drm/i915/display/intel_fb.c
> +++ b/drivers/gpu/drm/i915/display/intel_fb.c
> @@ -1287,7 +1287,7 @@ bool intel_plane_uses_fence(const struct intel_plane_state *plane_state)
>  	struct intel_display *display = to_intel_display(plane_state);
>  	struct intel_plane *plane = to_intel_plane(plane_state->uapi.plane);
>  
> -	return DISPLAY_VER(display) < 4 ||
> +	return intel_plane_needs_fence(display) ||
>  		(plane->fbc && !plane_state->no_fbc_reason &&
>  		 i915_gtt_view_is_normal(&plane_state->view.gtt));
>  }
> diff --git a/drivers/gpu/drm/i915/display/intel_plane.c b/drivers/gpu/drm/i915/display/intel_plane.c
> index f41f4c2ac320..c2b58d3b9c23 100644
> --- a/drivers/gpu/drm/i915/display/intel_plane.c
> +++ b/drivers/gpu/drm/i915/display/intel_plane.c
> @@ -192,6 +192,15 @@ bool intel_plane_needs_physical(struct intel_plane *plane)
>  		DISPLAY_INFO(display)->cursor_needs_physical;
>  }
>  
> +bool intel_plane_needs_fence(struct intel_display *display)
> +{
> +	/*
> +	 * pre-i965 planes use the fence for tiled scanout.
> +	 * i965+ planes have their own tiled scanout control bit.
> +	 */
> +	return DISPLAY_VER(display) < 4;
> +}
> +
>  bool intel_plane_can_async_flip(struct intel_plane *plane,
>  				const struct drm_format_info *info,
>  				u64 modifier)
> diff --git a/drivers/gpu/drm/i915/display/intel_plane.h b/drivers/gpu/drm/i915/display/intel_plane.h
> index 7fa7fbbb58dc..7b5456f56f42 100644
> --- a/drivers/gpu/drm/i915/display/intel_plane.h
> +++ b/drivers/gpu/drm/i915/display/intel_plane.h
> @@ -82,6 +82,7 @@ void intel_plane_set_invisible(struct intel_crtc_state *crtc_state,
>  void intel_plane_helper_add(struct intel_plane *plane);
>  bool intel_plane_needs_low_address(struct intel_display *display);
>  bool intel_plane_needs_physical(struct intel_plane *plane);
> +bool intel_plane_needs_fence(struct intel_display *display);
>  void intel_plane_init_cursor_vblank_work(struct intel_plane_state *old_plane_state,
>  					 struct intel_plane_state *new_plane_state);
>  int intel_plane_add_affected(struct intel_atomic_state *state,
> diff --git a/drivers/gpu/drm/i915/i915_fb_pin.c b/drivers/gpu/drm/i915/i915_fb_pin.c
> index bfe9a5342e13..a8ed888183cb 100644
> --- a/drivers/gpu/drm/i915/i915_fb_pin.c
> +++ b/drivers/gpu/drm/i915/i915_fb_pin.c
> @@ -188,7 +188,7 @@ intel_fb_pin_to_ggtt(const struct drm_framebuffer *fb,
>  		 * mode that matches the user configuration.
>  		 */
>  		ret = i915_vma_pin_fence(vma);
> -		if (ret != 0 && DISPLAY_VER(display) < 4) {
> +		if (ret != 0 && intel_plane_needs_fence(display)) {
>  			i915_vma_unpin(vma);
>  			goto err_unpin;
>  		}

-- 
Jani Nikula, Intel