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drm/vc4: plane: TPZ scaling modes cannot reduce lbm size when alpha-less #7164

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Merged
pelwell merged 2 commits into from
Dec 4, 2025
+4 −14
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drm/vc4: plane: TPZ scaling modes cannot reduce lbm size when alpha-less #7164

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476f31e
drm/vc4: plane: Remove dead channels_scaled code
popcornmix Dec 3, 2025
3b8d670
drm/vc4: plane: TPZ scaling modes cannot reduce lbm size when alpha-less
popcornmix Dec 3, 2025
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18 changes: 4 additions & 14 deletions drivers/gpu/drm/vc4/vc4_plane.c
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Original file line number Diff line number Diff line change
Expand Up @@ -802,7 +802,10 @@ static unsigned int vc4_lbm_components(const struct drm_plane_state *state,
if (info->is_yuv)
return channel ? 2 : 1;

if (info->has_alpha)
if (vc4_state->y_scaling[channel] == VC4_SCALING_TPZ)
return 4;

if (info->has_alpha && state->alpha == DRM_BLEND_ALPHA_OPAQUE)
return 4;

return 3;
Expand All @@ -812,11 +815,8 @@ static unsigned int vc4_lbm_channel_size(const struct drm_plane_state *state,
unsigned int channel)
{
const struct drm_format_info *info = state->fb->format;
const struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
unsigned int channels_scaled = 0;
unsigned int components, words, wpc;
unsigned int width, lines;
unsigned int i;

/* LBM is meant to use the smaller of source or dest width, but there
* is a issue with UV scaling that the size required for the second
Expand All @@ -836,20 +836,10 @@ static unsigned int vc4_lbm_channel_size(const struct drm_plane_state *state,
if (!components)
return 0;

if (state->alpha != DRM_BLEND_ALPHA_OPAQUE && info->has_alpha)
components -= 1;

words = width * wpc * components;

lines = DIV_ROUND_UP(words, 128 / info->hsub);

for (i = 0; i < 2; i++)
if (vc4_state->y_scaling[channel] != VC4_SCALING_NONE)
channels_scaled++;

if (channels_scaled == 1)
lines = lines / 2;

return lines;
}

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