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drm/vc4: Correct lbm size and calculation

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commit 78e5330329ee206d6aa4593a90320fd837f7966e upstream.

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 address indexes work in units of pixels per clock,
so for 4 pixels per clock that means we have 32 * 1920 = 60K

Fixes: c54619b0bf ("drm/vc4: Add support for the BCM2711 HVS5")
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Tested-By: Lucas Nussbaum <lucas@debian.org>
Tested-By: Ryutaroh Matsumoto <ryutaroh@ict.e.titech.ac.jp>
Link: https://patchwork.freedesktop.org/patch/msgid/20210121105759.1262699-1-maxime@cerno.tech
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dom Cobley
2021-01-21 11:57:58 +01:00
committed by Greg Kroah-Hartman
parent 112821f254
commit 21e3ad8054
2 changed files with 10 additions and 5 deletions
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7
drivers/gpu/drm/vc4/vc4_plane.c
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@@ -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;
}