Support a 1D gamma LUT with interpolation for each color channel on the
VKMS driver. Add a check for the LUT length by creating
vkms_atomic_check().
Tested with:
igt@kms_color@gamma
igt@kms_color@legacy-gamma
igt@kms_color@invalid-gamma-lut-sizes
v2:
- Add interpolation between the values of the LUT (Simon Ser)
Signed-off-by: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
---
drivers/gpu/drm/vkms/vkms_composer.c | 97 ++++++++++++++++++++++++++++
drivers/gpu/drm/vkms/vkms_crtc.c | 3 +
drivers/gpu/drm/vkms/vkms_drv.c | 20 +++++-
drivers/gpu/drm/vkms/vkms_drv.h | 2 +
4 files changed, 121 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index 906d3df40cdb..24bffd98ba49 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -6,6 +6,7 @@
#include <drm/drm_atomic_helper.h>
#include <drm/drm_blend.h>
#include <drm/drm_fourcc.h>
+#include <drm/drm_fixed.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_vblank.h>
#include <linux/minmax.h>
@@ -89,6 +90,100 @@ static void fill_background(const struct pixel_argb_u16 *background_color,
output_buffer->pixels[i] = *background_color;
}
+// lerp(a, b, t) = a + (b - a) * t
+static u16 lerp_u16(u16 a, u16 b, s64 t)
+{
+ s64 a_fp = drm_int2fixp(a);
+ s64 b_fp = drm_int2fixp(b);
+
+ s64 ratio = drm_fixp_mul(b_fp - a_fp, t);
+
+ return drm_fixp2int(a_fp + ratio);
+}
+
+static s64 get_lut_index(u16 color_channel, size_t lut_length)
+{
+ const s64 max_lut_index_fp = drm_int2fixp(lut_length - 1);
+ const s64 u16_max_fp = drm_int2fixp(0xffff);
+
+ s64 ratio = drm_fixp_div(max_lut_index_fp, u16_max_fp);
+
+ s64 color_channel_fp = drm_int2fixp(color_channel);
+
+ return drm_fixp_mul(color_channel_fp, ratio);
+}
+
+enum lut_area {
+ LUT_RED,
+ LUT_GREEN,
+ LUT_BLUE,
+ LUT_RESERVED
+};
+
+static void apply_lut_to_color_channel(u16 *color_channel, enum lut_area area,
+ struct drm_color_lut *lut, size_t lut_length)
+{
+ s64 ratio;
+
+ s64 lut_index = get_lut_index(*color_channel, lut_length);
+
+ size_t floor_index = drm_fixp2int(lut_index);
+ size_t ceil_index = drm_fixp2int_ceil(lut_index);
+
+ struct drm_color_lut floor_lut_value = lut[floor_index];
+ struct drm_color_lut ceil_lut_value = lut[ceil_index];
+
+ u16 floor_color_channel;
+ u16 ceil_color_channel;
+
+ switch (area) {
+ case LUT_RED:
+ floor_color_channel = floor_lut_value.red;
+ ceil_color_channel = ceil_lut_value.red;
+ break;
+ case LUT_GREEN:
+ floor_color_channel = floor_lut_value.green;
+ ceil_color_channel = ceil_lut_value.green;
+ break;
+ case LUT_BLUE:
+ floor_color_channel = floor_lut_value.blue;
+ ceil_color_channel = ceil_lut_value.blue;
+ break;
+ case LUT_RESERVED:
+ floor_color_channel = floor_lut_value.reserved;
+ ceil_color_channel = ceil_lut_value.reserved;
+ break;
+ }
+
+ ratio = lut_index - drm_int2fixp(floor_index);
+
+ *color_channel = lerp_u16(floor_color_channel, ceil_color_channel, ratio);
+}
+
+static void apply_lut(const struct vkms_crtc_state *crtc_state, struct line_buffer *output_buffer)
+{
+ struct drm_color_lut *lut;
+ size_t lut_length;
+
+ if (!crtc_state->base.gamma_lut)
+ return;
+
+ lut = (struct drm_color_lut *)crtc_state->base.gamma_lut->data;
+
+ lut_length = crtc_state->base.gamma_lut->length / sizeof(*lut);
+
+ if (!lut_length)
+ return;
+
+ for (size_t x = 0; x < output_buffer->n_pixels; x++) {
+ struct pixel_argb_u16 *pixel = &output_buffer->pixels[x];
+
+ apply_lut_to_color_channel(&pixel->r, LUT_RED, lut, lut_length);
+ apply_lut_to_color_channel(&pixel->g, LUT_GREEN, lut, lut_length);
+ apply_lut_to_color_channel(&pixel->b, LUT_BLUE, lut, lut_length);
+ }
+}
+
/**
* @wb_frame_info: The writeback frame buffer metadata
* @crtc_state: The crtc state
@@ -128,6 +223,8 @@ static void blend(struct vkms_writeback_job *wb,
output_buffer);
}
+ apply_lut(crtc_state, output_buffer);
+
*crc32 = crc32_le(*crc32, (void *)output_buffer->pixels, row_size);
if (wb)
diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 515f6772b866..61e500b8c9da 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -290,6 +290,9 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
drm_crtc_helper_add(crtc, &vkms_crtc_helper_funcs);
+ drm_mode_crtc_set_gamma_size(crtc, VKMS_LUT_SIZE);
+ drm_crtc_enable_color_mgmt(crtc, 0, false, VKMS_LUT_SIZE);
+
spin_lock_init(&vkms_out->lock);
spin_lock_init(&vkms_out->composer_lock);
diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
index e3c9c9571c8d..dd0af086e7fa 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.c
+++ b/drivers/gpu/drm/vkms/vkms_drv.c
@@ -120,9 +120,27 @@ static const struct drm_driver vkms_driver = {
.minor = DRIVER_MINOR,
};
+static int vkms_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
+{
+ struct drm_crtc *crtc;
+ struct drm_crtc_state *new_crtc_state;
+ int i;
+
+ for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
+ if (!new_crtc_state->gamma_lut || !new_crtc_state->color_mgmt_changed)
+ continue;
+
+ if (new_crtc_state->gamma_lut->length / sizeof(struct drm_color_lut *)
+ > VKMS_LUT_SIZE)
+ return -EINVAL;
+ }
+
+ return drm_atomic_helper_check(dev, state);
+}
+
static const struct drm_mode_config_funcs vkms_mode_funcs = {
.fb_create = drm_gem_fb_create,
- .atomic_check = drm_atomic_helper_check,
+ .atomic_check = vkms_atomic_check,
.atomic_commit = drm_atomic_helper_commit,
};
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index 5f1a0a44a78c..a3b7025c1b9a 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -23,6 +23,8 @@
#define NUM_OVERLAY_PLANES 8
+#define VKMS_LUT_SIZE 256
+
struct vkms_frame_info {
struct drm_framebuffer *fb;
struct drm_rect src, dst;
--
2.40.1
