Re: [PATCH v3 016/105] drm/vc4: plane: Improve LBM usage

On Wed, May 27, 2020 at 8:49 AM Maxime Ripard maxime@cerno.tech wrote:

From: Dave Stevenson dave.stevenson@raspberrypi.com

LBM allocations were always taking the worst case sizing of max(src_width, dst_width) * 16. This is significantly over the required sizing, and stops us rendering multiple 4k images to the screen.

Add some of the additional constraints to more accurately describe the LBM requirements.

Signed-off-by: Dave Stevenson dave.stevenson@raspberrypi.com Signed-off-by: Maxime Ripard maxime@cerno.tech

---

drivers/gpu/drm/vc4/vc4_plane.c | 31 ++++++++++++++++++++----------- 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c index 1575c05e3106..602927745f84 100644 --- a/drivers/gpu/drm/vc4/vc4_plane.c +++ b/drivers/gpu/drm/vc4/vc4_plane.c @@ -142,9 +142,10 @@ static const struct hvs_format *vc4_get_hvs_format(u32 drm_format) return NULL; }

-static enum vc4_scaling_mode vc4_get_scaling_mode(u32 src, u32 dst) +static enum vc4_scaling_mode vc4_get_scaling_mode(u32 src, u32 dst,

•                                             bool chroma_vrep)
  

{

•   if (dst == src)
  

•   if (dst == src && !chroma_vrep)
            return VC4_SCALING_NONE;
    if (3 * dst >= 2 * src)
            return VC4_SCALING_PPF;
  

@@ -369,9 +370,11 @@ static int vc4_plane_setup_clipping_and_scaling(struct drm_plane_state *state) return ret;

    vc4_state->x_scaling[0] = vc4_get_scaling_mode(vc4_state->src_w[0],

•                                                  vc4_state->crtc_w);
  

•                                                  vc4_state->crtc_w,
  

•                                                  false);
    vc4_state->y_scaling[0] = vc4_get_scaling_mode(vc4_state->src_h[0],
  

•                                                  vc4_state->crtc_h);
  

•                                                  vc4_state->crtc_h,
  

•                                                  false);
  
    vc4_state->is_unity = (vc4_state->x_scaling[0] == VC4_SCALING_NONE &&
                           vc4_state->y_scaling[0] == VC4_SCALING_NONE);
  

@@ -384,10 +387,12 @@ static int vc4_plane_setup_clipping_and_scaling(struct drm_plane_state *state)

            vc4_state->x_scaling[1] =
                    vc4_get_scaling_mode(vc4_state->src_w[1],

•                                        vc4_state->crtc_w);
  

•                                        vc4_state->crtc_w,
  

•                                        v_subsample == 2);
            vc4_state->y_scaling[1] =
                    vc4_get_scaling_mode(vc4_state->src_h[1],
  

•                                        vc4_state->crtc_h);
  

•                                        vc4_state->crtc_h,
  

•                                        v_subsample == 2);
  
            /* YUV conversion requires that horizontal scaling be enabled
             * on the UV plane even if vc4_get_scaling_mode() returned
  

The change above isn't mentioned in the commit message and I don't understand what's going on. It should be split out with an explanation.

@@ -437,10 +442,7 @@ static void vc4_write_ppf(struct vc4_plane_state *vc4_state, u32 src, u32 dst) static u32 vc4_lbm_size(struct drm_plane_state *state) { struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);

•   /* This is the worst case number.  One of the two sizes will
  

•    * be used depending on the scaling configuration.
  

•    */
  

•   u32 pix_per_line = max(vc4_state->src_w[0], (u32)vc4_state->crtc_w);
  

•   u32 pix_per_line;
    u32 lbm;
  
    /* LBM is not needed when there's no vertical scaling. */
  

@@ -448,6 +450,11 @@ static u32 vc4_lbm_size(struct drm_plane_state *state) vc4_state->y_scaling[1] == VC4_SCALING_NONE) return 0;

•   if (vc4_state->x_scaling[0] == VC4_SCALING_TPZ)
  

•           pix_per_line = vc4_state->crtc_w;
  

•   else
  

•           pix_per_line = vc4_state->src_w[0];
  

Looks like it's also crtc_w for RGB or 4:4:4 and HPPF in (0.5,1.0]. Maybe drop a note in here that we're not covering that case, but src_w

crtc_w so it's safe at least.

•   if (!vc4_state->is_yuv) {
            if (vc4_state->y_scaling[0] == VC4_SCALING_TPZ)
                    lbm = pix_per_line * 8;
  

@@ -583,7 +590,9 @@ static int vc4_plane_allocate_lbm(struct drm_plane_state *state) spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags); ret = drm_mm_insert_node_generic(&vc4->hvs->lbm_mm, &vc4_state->lbm,

•                                            lbm_size, 32, 0, 0);
  

•                                            lbm_size,
  

•                                            vc4->hvs->hvs5 ? 64 : 32,
  

•                                            0, 0);
            spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
  
            if (ret)
  

-- git-series 0.9.1