1 files changed, 93 insertions, 2 deletions

diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index d170a8e89b95..d5d4f642d367 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 +90,73 @@ 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 delta = drm_fixp_mul(b_fp - a_fp,  t);
+
+	return drm_fixp2int(a_fp + delta);
+}
+
+static s64 get_lut_index(const struct vkms_color_lut *lut, u16 channel_value)
+{
+	s64 color_channel_fp = drm_int2fixp(channel_value);
+
+	return drm_fixp_mul(color_channel_fp, lut->channel_value2index_ratio);
+}
+
+/*
+ * This enum is related to the positions of the variables inside
+ * `struct drm_color_lut`, so the order of both needs to be the same.
+ */
+enum lut_channel {
+	LUT_RED = 0,
+	LUT_GREEN,
+	LUT_BLUE,
+	LUT_RESERVED
+};
+
+static u16 apply_lut_to_channel_value(const struct vkms_color_lut *lut, u16 channel_value,
+				      enum lut_channel channel)
+{
+	s64 lut_index = get_lut_index(lut, channel_value);
+
+	/*
+	 * This checks if `struct drm_color_lut` has any gap added by the compiler
+	 * between the struct fields.
+	 */
+	static_assert(sizeof(struct drm_color_lut) == sizeof(__u16) * 4);
+
+	u16 *floor_lut_value = (__u16 *)&lut->base[drm_fixp2int(lut_index)];
+	u16 *ceil_lut_value = (__u16 *)&lut->base[drm_fixp2int_ceil(lut_index)];
+
+	u16 floor_channel_value = floor_lut_value[channel];
+	u16 ceil_channel_value = ceil_lut_value[channel];
+
+	return lerp_u16(floor_channel_value, ceil_channel_value,
+			lut_index & DRM_FIXED_DECIMAL_MASK);
+}
+
+static void apply_lut(const struct vkms_crtc_state *crtc_state, struct line_buffer *output_buffer)
+{
+	if (!crtc_state->gamma_lut.base)
+		return;
+
+	if (!crtc_state->gamma_lut.lut_length)
+		return;
+
+	for (size_t x = 0; x < output_buffer->n_pixels; x++) {
+		struct pixel_argb_u16 *pixel = &output_buffer->pixels[x];
+
+		pixel->r = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->r, LUT_RED);
+		pixel->g = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->g, LUT_GREEN);
+		pixel->b = apply_lut_to_channel_value(&crtc_state->gamma_lut, pixel->b, LUT_BLUE);
+	}
+}
+
 /**
  * blend - blend the pixels from all planes and compute crc
  * @wb: The writeback frame buffer metadata
@@ -130,6 +198,8 @@ 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)
@@ -244,6 +314,22 @@ void vkms_composer_worker(struct work_struct *work)
 	crtc_state->frame_start = 0;
 	crtc_state->frame_end = 0;
 	crtc_state->crc_pending = false;
+
+	if (crtc->state->gamma_lut) {
+		s64 max_lut_index_fp;
+		s64 u16_max_fp = drm_int2fixp(0xffff);
+
+		crtc_state->gamma_lut.base = (struct drm_color_lut *)crtc->state->gamma_lut->data;
+		crtc_state->gamma_lut.lut_length =
+			crtc->state->gamma_lut->length / sizeof(struct drm_color_lut);
+		max_lut_index_fp = drm_int2fixp(crtc_state->gamma_lut.lut_length  - 1);
+		crtc_state->gamma_lut.channel_value2index_ratio = drm_fixp_div(max_lut_index_fp,
+									       u16_max_fp);
+
+	} else {
+		crtc_state->gamma_lut.base = NULL;
+	}
+
 	spin_unlock_irq(&out->composer_lock);
 
 	/*
@@ -322,10 +408,15 @@ void vkms_set_composer(struct vkms_output *out, bool enabled)
 	if (enabled)
 		drm_crtc_vblank_get(&out->crtc);
 
-	spin_lock_irq(&out->lock);
+	mutex_lock(&out->enabled_lock);
 	old_enabled = out->composer_enabled;
 	out->composer_enabled = enabled;
-	spin_unlock_irq(&out->lock);
+
+	/* the composition wasn't enabled, so unlock the lock to make sure the lock
+	 * will be balanced even if we have a failed commit
+	 */
+	if (!out->composer_enabled)
+		mutex_unlock(&out->enabled_lock);
 
 	if (old_enabled)
 		drm_crtc_vblank_put(&out->crtc);