Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
drm/color-mgmt: Prepare for RGB332 palettes
Add helper drm_crtc_fill_palette_332(), which fills palettes with
RGB332 color data. Each color in RGB332 format serves as an index
into an 8-bit palette that stores the corresponding component-based
colors.
Vesadrm will use the new helper to emulate RGB formats on top of
framebuffers in C8 format.
v2:
- add comments on bit operations (Javier)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250714151513.309475-6-tzimmermann@suse.de
+35
+34
drivers/gpu/drm/drm_color_mgmt.c
+34
drivers/gpu/drm/drm_color_mgmt.c
···
817
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}
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EXPORT_SYMBOL(drm_crtc_load_palette_8);
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820
+
static void fill_palette_332(struct drm_crtc *crtc, u16 r, u16 g, u16 b,
821
+
drm_crtc_set_lut_func set_palette)
822
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{
823
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unsigned int i = (r << 5) | (g << 2) | b; /* 8-bit palette index */
824
+
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/* Expand R (3-bit) G (3-bit) and B (2-bit) values to 16-bit values */
826
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r = (r << 13) | (r << 10) | (r << 7) | (r << 4) | (r << 1) | (r >> 2);
827
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g = (g << 13) | (g << 10) | (g << 7) | (g << 4) | (g << 1) | (g >> 2);
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b = (b << 14) | (b << 12) | (b << 10) | (b << 8) | (b << 6) | (b << 4) | (b << 2) | b;
829
+
830
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set_palette(crtc, i, r, g, b);
831
+
}
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+
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/**
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* drm_crtc_fill_palette_332 - Programs a default palette for R332-like formats
835
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* @crtc: The displaying CRTC
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* @set_palette: Callback for programming the hardware gamma LUT
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*
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* Programs an RGB332 palette to hardware.
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*/
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void drm_crtc_fill_palette_332(struct drm_crtc *crtc, drm_crtc_set_lut_func set_palette)
841
+
{
842
+
unsigned int r, g, b;
843
+
844
+
/* Limits of 8-8-4 are the maximum number of values for each channel. */
845
+
for (r = 0; r < 8; ++r) {
846
+
for (g = 0; g < 8; ++g) {
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+
for (b = 0; b < 4; ++b)
848
+
fill_palette_332(crtc, r, g, b, set_palette);
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+
}
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}
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+
}
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+
EXPORT_SYMBOL(drm_crtc_fill_palette_332);
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+
820
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static void fill_palette_8(struct drm_crtc *crtc, unsigned int i,
821
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drm_crtc_set_lut_func set_palette)
822
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{
+1
include/drm/drm_color_mgmt.h
+1
include/drm/drm_color_mgmt.h
···
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void drm_crtc_load_palette_8(struct drm_crtc *crtc, const struct drm_color_lut *lut,
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drm_crtc_set_lut_func set_palette);
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+
void drm_crtc_fill_palette_332(struct drm_crtc *crtc, drm_crtc_set_lut_func set_palette);
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void drm_crtc_fill_palette_8(struct drm_crtc *crtc, drm_crtc_set_lut_func set_palette);
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#endif