Re: [PATCH v8 6/7] drm/i915/fbc: dirty rect support for FBC

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Feb 13, 2025 at 03:25:57PM +0200, Vinod Govindapillai wrote:
> Dirty rectangle feature allows FBC to recompress a subsection
> of a frame. When this feature is enabled, display will read
> the scan lines between dirty rectangle start line and dirty
> rectangle end line in subsequent frames.
> 
> Use the merged damage clip stored in the plane state to
> configure the FBC dirty rect areas.
> 
> v2: - Move dirty rect handling to fbc state (Ville)
> 
> v3: - Use intel_fbc_dirty_rect_update_noarm (Ville)
>     - Split plane damage collection and dirty rect preparation
>     - Handle case where dirty rect fall outside the visible region
> 
> v4: - A state variable to check if we need to update dirty rect
>     registers in case intel_fbc_can_flip_nuke() (Ville)
> 
> v5: - No need to use a separate valid flag, updates to the
>       conditions for prepare damage rect (Ville)
>     - Usage of locks in fbc dirty rect related functions (Ville)
> 
> v6: - updates dirty rect handling (Ville)
> 
> Bspec: 68881, 71675, 73424
> Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
> ---
>  .../gpu/drm/i915/display/intel_atomic_plane.c |  3 +
>  drivers/gpu/drm/i915/display/intel_display.c  |  3 +
>  drivers/gpu/drm/i915/display/intel_fbc.c      | 85 +++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_fbc.h      |  5 ++
>  4 files changed, 96 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> index 2278412200fd..041e1d9ef621 100644
> --- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> +++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
> @@ -803,6 +803,9 @@ void intel_plane_update_noarm(struct intel_dsb *dsb,
>  
>  	trace_intel_plane_update_noarm(plane_state, crtc);
>  
> +	if (plane->fbc)
> +		intel_fbc_dirty_rect_update_noarm(dsb, plane);
> +
>  	if (plane->update_noarm)
>  		plane->update_noarm(dsb, plane, crtc_state, plane_state);
>  }
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index cc51576353fe..dd801b9d9a52 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -7783,6 +7783,9 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state)
>  
>  	intel_atomic_prepare_plane_clear_colors(state);
>  
> +	for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i)
> +		intel_fbc_prepare_dirty_rect(state, crtc);
> +
>  	for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i)
>  		intel_atomic_dsb_finish(state, crtc);
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> index d2917e017e7b..66a5ee10a649 100644
> --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> @@ -88,6 +88,7 @@ struct intel_fbc_state {
>  	u16 override_cfb_stride;
>  	u16 interval;
>  	s8 fence_id;
> +	struct drm_rect dirty_rect;
>  };
>  
>  struct intel_fbc {
> @@ -527,6 +528,9 @@ static void ilk_fbc_deactivate(struct intel_fbc *fbc)
>  	struct intel_display *display = fbc->display;
>  	u32 dpfc_ctl;
>  
> +	if (HAS_FBC_DIRTY_RECT(display))
> +		intel_de_write(display, XE3_FBC_DIRTY_CTL(fbc->id), 0);
> +
>  	/* Disable compression */
>  	dpfc_ctl = intel_de_read(display, ILK_DPFC_CONTROL(fbc->id));
>  	if (dpfc_ctl & DPFC_CTL_EN) {
> @@ -670,6 +674,10 @@ static void ivb_fbc_activate(struct intel_fbc *fbc)
>  	if (DISPLAY_VER(display) >= 20)
>  		intel_de_write(display, ILK_DPFC_CONTROL(fbc->id), dpfc_ctl);
>  
> +	if (HAS_FBC_DIRTY_RECT(display))
> +		intel_de_write(display, XE3_FBC_DIRTY_CTL(fbc->id),
> +			       FBC_DIRTY_RECT_EN);
> +
>  	intel_de_write(display, ILK_DPFC_CONTROL(fbc->id),
>  		       DPFC_CTL_EN | dpfc_ctl);
>  }
> @@ -1214,6 +1222,83 @@ static bool tiling_is_valid(const struct intel_plane_state *plane_state)
>  		return i8xx_fbc_tiling_valid(plane_state);
>  }
>  
> +static void
> +intel_fbc_dirty_rect_update(struct intel_dsb *dsb, struct intel_fbc *fbc)
> +{
> +	struct intel_display *display = fbc->display;
> +	struct drm_rect *fbc_dirty_rect = &fbc->state.dirty_rect;

can be const

> +
> +	lockdep_assert_held(&fbc->lock);
> +
> +	intel_de_write_dsb(display, dsb, XE3_FBC_DIRTY_RECT(fbc->id),
> +			   FBC_DIRTY_RECT_START_LINE(fbc_dirty_rect->y1) |
> +			   FBC_DIRTY_RECT_END_LINE(fbc_dirty_rect->y2 - 1));
> +}
> +
> +void
> +intel_fbc_dirty_rect_update_noarm(struct intel_dsb *dsb,
> +				  struct intel_plane *plane)
> +{
> +	struct intel_display *display = to_intel_display(plane);
> +	struct intel_fbc *fbc = plane->fbc;
> +
> +	if (!HAS_FBC_DIRTY_RECT(display))
> +		return;
> +
> +	mutex_lock(&fbc->lock);
> +
> +	if (fbc->state.plane == plane)
> +		intel_fbc_dirty_rect_update(dsb, fbc);
> +
> +	mutex_unlock(&fbc->lock);
> +}
> +
> +static void
> +__intel_fbc_prepare_dirty_rect(struct intel_plane *plane,

plane doesn't need to be passed in explicitly since it can
be determined from the plane_state.

> +			       struct intel_plane_state *plane_state)

this can be const.

> +{
> +	struct intel_fbc *fbc = plane->fbc;
> +	struct drm_rect *fbc_dirty_rect = &fbc->state.dirty_rect;
> +	int width = drm_rect_width(&plane_state->uapi.src) >> 16;
> +	const struct drm_rect *damage = &plane_state->damage;
> +	int y_offset = plane_state->view.color_plane[0].y;
> +
> +	lockdep_assert_held(&fbc->lock);
> +
> +	if (drm_rect_visible(damage))
> +		*fbc_dirty_rect = *damage;
> +	else
> +		/* dirty rect must cover at least one line */
> +		*fbc_dirty_rect = DRM_RECT_INIT(0, y_offset, width, 1);
> +}
> +
> +void
> +intel_fbc_prepare_dirty_rect(struct intel_atomic_state *state,
> +			     struct intel_crtc *crtc)

Looks to me like we don't actully need the crtc here at all.
We anyway just end up looping through all the planes in the
state.

With those sorted the series is
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +{
> +	struct intel_display *display = to_intel_display(state);
> +	struct intel_plane_state *plane_state;
> +	struct intel_plane *plane;
> +	int i;
> +
> +	if (!HAS_FBC_DIRTY_RECT(display))
> +		return;
> +
> +	for_each_new_intel_plane_in_state(state, plane, plane_state, i) {
> +		struct intel_fbc *fbc = plane->fbc;
> +
> +		if (!fbc || plane->pipe != crtc->pipe)
> +			continue;
> +
> +		mutex_lock(&fbc->lock);
> +
> +		if (fbc->state.plane == plane)
> +			__intel_fbc_prepare_dirty_rect(plane, plane_state);
> +
> +		mutex_unlock(&fbc->lock);
> +	}
> +}
> +
>  static void intel_fbc_update_state(struct intel_atomic_state *state,
>  				   struct intel_crtc *crtc,
>  				   struct intel_plane *plane)
> diff --git a/drivers/gpu/drm/i915/display/intel_fbc.h b/drivers/gpu/drm/i915/display/intel_fbc.h
> index ceae55458e14..fe48d0276eec 100644
> --- a/drivers/gpu/drm/i915/display/intel_fbc.h
> +++ b/drivers/gpu/drm/i915/display/intel_fbc.h
> @@ -14,6 +14,7 @@ struct intel_atomic_state;
>  struct intel_crtc;
>  struct intel_crtc_state;
>  struct intel_display;
> +struct intel_dsb;
>  struct intel_fbc;
>  struct intel_plane;
>  struct intel_plane_state;
> @@ -48,5 +49,9 @@ void intel_fbc_handle_fifo_underrun_irq(struct intel_display *display);
>  void intel_fbc_reset_underrun(struct intel_display *display);
>  void intel_fbc_crtc_debugfs_add(struct intel_crtc *crtc);
>  void intel_fbc_debugfs_register(struct intel_display *display);
> +void intel_fbc_prepare_dirty_rect(struct intel_atomic_state *state,
> +				  struct intel_crtc *crtc);
> +void intel_fbc_dirty_rect_update_noarm(struct intel_dsb *dsb,
> +				       struct intel_plane *plane);
>  
>  #endif /* __INTEL_FBC_H__ */
> -- 
> 2.43.0

-- 
Ville Syrjälä
Intel