Am 11.07.25 um 14:30 schrieb Thomas Zimmermann:
Hi
Am 11.07.25 um 14:24 schrieb Javier Martinez Canillas:
Thomas Zimmermann <[email protected]> writes:
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.
Signed-off-by: Thomas Zimmermann <[email protected]>
---
drivers/gpu/drm/drm_color_mgmt.c | 32
++++++++++++++++++++++++++++++++
include/drm/drm_color_mgmt.h | 1 +
2 files changed, 33 insertions(+)
diff --git a/drivers/gpu/drm/drm_color_mgmt.c
b/drivers/gpu/drm/drm_color_mgmt.c
index 37a3270bc3c2..7ef214848313 100644
--- a/drivers/gpu/drm/drm_color_mgmt.c
+++ b/drivers/gpu/drm/drm_color_mgmt.c
@@ -817,6 +817,38 @@ void drm_crtc_load_palette_8(struct drm_crtc
*crtc, const struct drm_color_lut *
}
EXPORT_SYMBOL(drm_crtc_load_palette_8);
+static void fill_palette_332(struct drm_crtc *crtc, u16 r, u16 g,
u16 b,
+ drm_crtc_set_lut_func set_palette)
+{
+ unsigned int i = (r << 5) | (g << 2) | b;
+
+ r = (r << 13) | (r << 10) | (r << 7) | (r << 4) | (r << 1) | (r
>> 2);
+ g = (g << 13) | (g << 10) | (g << 7) | (g << 4) | (g << 1) | (g
>> 2);
+ b = (b << 14) | (b << 12) | (b << 10) | (b << 8) | (b << 6) |
(b << 4) | (b << 2) | b;
+
+ set_palette(crtc, i, r, g, b);
+}
I think this helper can benefit of having a kernel-doc or some code
comments, e.g:
/* Calculate the 8-bit palette index from the color
components */
unsigned int i = (r << 5) | (g << 2) | b;
/* Expand R (3-bit) G (3-bit) and B (2-bit) values to
16-bit depth colors */
r = (r << 13) | (r << 10) | (r << 7) | (r << 4) | (r << 1)
| (r >> 2);
g = (g << 13) | (g << 10) | (g << 7) | (g << 4) | (g << 1)
| (g >> 2);
b = (b << 14) | (b << 12) | (b << 10) | (b << 8) | (b <<
6) | (b << 4) | (b << 2) | b;
/* Call the drivers' specific callback to program the
hardware LUT */
set_palette(crtc, i, r, g, b);
It might be evident to you, but I don't think it will be for others
looking
at the code later.
The code itself looks good to me, if I understood it correctly :)
Thanks for reviewing. Commenting this code makes sense. I just looked
again at the r-g-b for loop and the limits are incorrect. Needs to by
3-3-2 instead of 8-8-4. IDK how that happened, as the screenshot from
the test looks correct.
https://imgur.com/a/vesadrm-day4-z2XQ4wA
Anyway that is another fix here.
And looking at it again, 8-8-4 is actually correct. It's just
non-obvious even to the code's author. Hence some docs/changes are needed.
Best regards
Thomas
Reviewed-by: Javier Martinez Canillas <[email protected]>
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
