Hi Maxime
On Thu, 21 Jan 2021 at 10:58, Maxime Ripard <maxime@xxxxxxxxxx> wrote:
>
> From: Dom Cobley <popcornmix@xxxxxxxxx>
>
> LBM base address is measured in units of pixels per cycle.
> That is 4 for 2711 (hvs5) and 2 for 2708.
>
> We are wasting 75% of lbm by indexing without the scaling.
> But we were also using too high a size for the lbm resulting
> in partial corruption (right hand side) of vertically
> scaled images, usually at 4K or lower resolutions with more layers.
>
> The physical RAM of LBM on 2711 is 8 * 1920 * 16 * 12-bit
> (pixels are stored 12-bits per component regardless of format).
>
> The LBM adress indexes work in units of pixels per clock,
> so for 4 pixels per clock that means we have 32 * 1920 = 60K
>
> Fixes: c54619b0bfb3 ("drm/vc4: Add support for the BCM2711 HVS5")
> Signed-off-by: Dom Cobley <popcornmix@xxxxxxxxx>
> Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>
Reviewed-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/vc4/vc4_hvs.c | 8 ++++----
> drivers/gpu/drm/vc4/vc4_plane.c | 7 ++++++-
> 2 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_hvs.c b/drivers/gpu/drm/vc4/vc4_hvs.c
> index 2b3a597fa65f..c239045e05d6 100644
> --- a/drivers/gpu/drm/vc4/vc4_hvs.c
> +++ b/drivers/gpu/drm/vc4/vc4_hvs.c
> @@ -622,11 +622,11 @@ static int vc4_hvs_bind(struct device *dev, struct device *master, void *data)
> * for now we just allocate globally.
> */
> if (!hvs->hvs5)
> - /* 96kB */
> - drm_mm_init(&hvs->lbm_mm, 0, 96 * 1024);
> + /* 48k words of 2x12-bit pixels */
> + drm_mm_init(&hvs->lbm_mm, 0, 48 * 1024);
> else
> - /* 70k words */
> - drm_mm_init(&hvs->lbm_mm, 0, 70 * 2 * 1024);
> + /* 60k words of 4x12-bit pixels */
> + drm_mm_init(&hvs->lbm_mm, 0, 60 * 1024);
>
> /* Upload filter kernels. We only have the one for now, so we
> * keep it around for the lifetime of the driver.
> diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
> index 6bd8260aa9f2..b98eabb52920 100644
> --- a/drivers/gpu/drm/vc4/vc4_plane.c
> +++ b/drivers/gpu/drm/vc4/vc4_plane.c
> @@ -437,6 +437,7 @@ 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);
> + struct vc4_dev *vc4 = to_vc4_dev(state->plane->dev);
> u32 pix_per_line;
> u32 lbm;
>
> @@ -472,7 +473,11 @@ static u32 vc4_lbm_size(struct drm_plane_state *state)
> lbm = pix_per_line * 16;
> }
>
> - lbm = roundup(lbm, 32);
> + /* Align it to 64 or 128 (hvs5) bytes */
> + lbm = roundup(lbm, vc4->hvs->hvs5 ? 128 : 64);
> +
> + /* Each "word" of the LBM memory contains 2 or 4 (hvs5) pixels */
> + lbm /= vc4->hvs->hvs5 ? 4 : 2;
>
> return lbm;
> }
> --
> 2.29.2
>
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