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drm/ofdrm: Use helpers for programming gamma ramps

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Replace ofdrm's code for programming the hardware gamma LUT with
DRM helpers. Either load a provided gamma ramp or program a default.
Set the individual entries with a callback.

Each gamma value is given as 3 individual 16-bit values for red,
green and blue. The driver reduces them to 8 bit to make them fit
into hardware registers.

v2:
- fix coding style

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20250520094203.30545-5-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2025-05-20 11:40:06 +02:00
parent 1bdb883d65
commit a4871e6201
1 changed files with 30 additions and 50 deletions
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80
drivers/gpu/drm/sysfb/ofdrm.c
View File

@ -8,6 +8,7 @@
#include <drm/clients/drm_client_setup.h>
#include <drm/drm_atomic.h>
#include <drm/drm_atomic_state_helper.h>
#include <drm/drm_color_mgmt.h>
#include <drm/drm_connector.h>
#include <drm/drm_damage_helper.h>
#include <drm/drm_device.h>
@ -644,36 +645,36 @@ static void ofdrm_qemu_cmap_write(struct ofdrm_device *odev, unsigned char index
writeb(b, data);
}
static void ofdrm_device_set_gamma_linear(struct ofdrm_device *odev,
const struct drm_format_info *format)
static void ofdrm_set_gamma_lut(struct drm_crtc *crtc, unsigned int index,
u16 red, u16 green, u16 blue)
{
struct drm_device *dev = crtc->dev;
struct ofdrm_device *odev = ofdrm_device_of_dev(dev);
u8 i8 = index & 0xff;
u8 r8 = red >> 8;
u8 g8 = green >> 8;
u8 b8 = blue >> 8;
if (drm_WARN_ON_ONCE(dev, index != i8))
return; /* driver bug */
odev->funcs->cmap_write(odev, i8, r8, g8, b8);
}
static void ofdrm_device_fill_gamma(struct ofdrm_device *odev,
const struct drm_format_info *format)
{
struct drm_device *dev = &odev->sysfb.dev;
int i;
struct drm_crtc *crtc = &odev->crtc;
switch (format->format) {
case DRM_FORMAT_RGB565:
case DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN:
/* Use better interpolation, to take 32 values from 0 to 255 */
for (i = 0; i < OFDRM_GAMMA_LUT_SIZE / 8; i++) {
unsigned char r = i * 8 + i / 4;
unsigned char g = i * 4 + i / 16;
unsigned char b = i * 8 + i / 4;
odev->funcs->cmap_write(odev, i, r, g, b);
}
/* Green has one more bit, so add padding with 0 for red and blue. */
for (i = OFDRM_GAMMA_LUT_SIZE / 8; i < OFDRM_GAMMA_LUT_SIZE / 4; i++) {
unsigned char r = 0;
unsigned char g = i * 4 + i / 16;
unsigned char b = 0;
odev->funcs->cmap_write(odev, i, r, g, b);
}
drm_crtc_fill_gamma_565(crtc, ofdrm_set_gamma_lut);
break;
case DRM_FORMAT_XRGB8888:
case DRM_FORMAT_BGRX8888:
for (i = 0; i < OFDRM_GAMMA_LUT_SIZE; i++)
odev->funcs->cmap_write(odev, i, i, i, i);
drm_crtc_fill_gamma_888(crtc, ofdrm_set_gamma_lut);
break;
default:
drm_warn_once(dev, "Unsupported format %p4cc for gamma correction\n",
@ -682,42 +683,21 @@ static void ofdrm_device_set_gamma_linear(struct ofdrm_device *odev,
}
}
static void ofdrm_device_set_gamma(struct ofdrm_device *odev,
const struct drm_format_info *format,
struct drm_color_lut *lut)
static void ofdrm_device_load_gamma(struct ofdrm_device *odev,
const struct drm_format_info *format,
struct drm_color_lut *lut)
{
struct drm_device *dev = &odev->sysfb.dev;
int i;
struct drm_crtc *crtc = &odev->crtc;
switch (format->format) {
case DRM_FORMAT_RGB565:
case DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN:
/* Use better interpolation, to take 32 values from lut[0] to lut[255] */
for (i = 0; i < OFDRM_GAMMA_LUT_SIZE / 8; i++) {
unsigned char r = lut[i * 8 + i / 4].red >> 8;
unsigned char g = lut[i * 4 + i / 16].green >> 8;
unsigned char b = lut[i * 8 + i / 4].blue >> 8;
odev->funcs->cmap_write(odev, i, r, g, b);
}
/* Green has one more bit, so add padding with 0 for red and blue. */
for (i = OFDRM_GAMMA_LUT_SIZE / 8; i < OFDRM_GAMMA_LUT_SIZE / 4; i++) {
unsigned char r = 0;
unsigned char g = lut[i * 4 + i / 16].green >> 8;
unsigned char b = 0;
odev->funcs->cmap_write(odev, i, r, g, b);
}
drm_crtc_load_gamma_565_from_888(crtc, lut, ofdrm_set_gamma_lut);
break;
case DRM_FORMAT_XRGB8888:
case DRM_FORMAT_BGRX8888:
for (i = 0; i < OFDRM_GAMMA_LUT_SIZE; i++) {
unsigned char r = lut[i].red >> 8;
unsigned char g = lut[i].green >> 8;
unsigned char b = lut[i].blue >> 8;
odev->funcs->cmap_write(odev, i, r, g, b);
}
drm_crtc_load_gamma_888(crtc, lut, ofdrm_set_gamma_lut);
break;
default:
drm_warn_once(dev, "Unsupported format %p4cc for gamma correction\n",
@ -753,9 +733,9 @@ static void ofdrm_crtc_helper_atomic_flush(struct drm_crtc *crtc, struct drm_ato
const struct drm_format_info *format = sysfb_crtc_state->format;
if (crtc_state->gamma_lut)
ofdrm_device_set_gamma(odev, format, crtc_state->gamma_lut->data);
ofdrm_device_load_gamma(odev, format, crtc_state->gamma_lut->data);
else
ofdrm_device_set_gamma_linear(odev, format);
ofdrm_device_fill_gamma(odev, format);
}
}