1 files changed, 431 insertions, 0 deletions
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
new file mode 100644
index 000000000..3c99fb8b5
--- /dev/null
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -0,0 +1,431 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/crc32.h>
+
+#include <drm/drm_atomic.h>
+#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>
+
+#include "vkms_drv.h"
+
+static u16 pre_mul_blend_channel(u16 src, u16 dst, u16 alpha)
+{
+	u32 new_color;
+
+	new_color = (src * 0xffff + dst * (0xffff - alpha));
+
+	return DIV_ROUND_CLOSEST(new_color, 0xffff);
+}
+
+/**
+ * pre_mul_alpha_blend - alpha blending equation
+ * @frame_info: Source framebuffer's metadata
+ * @stage_buffer: The line with the pixels from src_plane
+ * @output_buffer: A line buffer that receives all the blends output
+ *
+ * Using the information from the `frame_info`, this blends only the
+ * necessary pixels from the `stage_buffer` to the `output_buffer`
+ * using premultiplied blend formula.
+ *
+ * The current DRM assumption is that pixel color values have been already
+ * pre-multiplied with the alpha channel values. See more
+ * drm_plane_create_blend_mode_property(). Also, this formula assumes a
+ * completely opaque background.
+ */
+static void pre_mul_alpha_blend(struct vkms_frame_info *frame_info,
+				struct line_buffer *stage_buffer,
+				struct line_buffer *output_buffer)
+{
+	int x_dst = frame_info->dst.x1;
+	struct pixel_argb_u16 *out = output_buffer->pixels + x_dst;
+	struct pixel_argb_u16 *in = stage_buffer->pixels;
+	int x_limit = min_t(size_t, drm_rect_width(&frame_info->dst),
+			    stage_buffer->n_pixels);
+
+	for (int x = 0; x < x_limit; x++) {
+		out[x].a = (u16)0xffff;
+		out[x].r = pre_mul_blend_channel(in[x].r, out[x].r, in[x].a);
+		out[x].g = pre_mul_blend_channel(in[x].g, out[x].g, in[x].a);
+		out[x].b = pre_mul_blend_channel(in[x].b, out[x].b, in[x].a);
+	}
+}
+
+static int get_y_pos(struct vkms_frame_info *frame_info, int y)
+{
+	if (frame_info->rotation & DRM_MODE_REFLECT_Y)
+		return drm_rect_height(&frame_info->rotated) - y - 1;
+
+	switch (frame_info->rotation & DRM_MODE_ROTATE_MASK) {
+	case DRM_MODE_ROTATE_90:
+		return frame_info->rotated.x2 - y - 1;
+	case DRM_MODE_ROTATE_270:
+		return y + frame_info->rotated.x1;
+	default:
+		return y;
+	}
+}
+
+static bool check_limit(struct vkms_frame_info *frame_info, int pos)
+{
+	if (drm_rotation_90_or_270(frame_info->rotation)) {
+		if (pos >= 0 && pos < drm_rect_width(&frame_info->rotated))
+			return true;
+	} else {
+		if (pos >= frame_info->rotated.y1 && pos < frame_info->rotated.y2)
+			return true;
+	}
+
+	return false;
+}
+
+static void fill_background(const struct pixel_argb_u16 *background_color,
+			    struct line_buffer *output_buffer)
+{
+	for (size_t i = 0; i < output_buffer->n_pixels; i++)
+		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
+ * @crtc_state: The crtc state
+ * @crc32: The crc output of the final frame
+ * @output_buffer: A buffer of a row that will receive the result of the blend(s)
+ * @stage_buffer: The line with the pixels from plane being blend to the output
+ * @row_size: The size, in bytes, of a single row
+ *
+ * This function blends the pixels (Using the `pre_mul_alpha_blend`)
+ * from all planes, calculates the crc32 of the output from the former step,
+ * and, if necessary, convert and store the output to the writeback buffer.
+ */
+static void blend(struct vkms_writeback_job *wb,
+		  struct vkms_crtc_state *crtc_state,
+		  u32 *crc32, struct line_buffer *stage_buffer,
+		  struct line_buffer *output_buffer, size_t row_size)
+{
+	struct vkms_plane_state **plane = crtc_state->active_planes;
+	u32 n_active_planes = crtc_state->num_active_planes;
+	int y_pos;
+
+	const struct pixel_argb_u16 background_color = { .a = 0xffff };
+
+	size_t crtc_y_limit = crtc_state->base.crtc->mode.vdisplay;
+
+	for (size_t y = 0; y < crtc_y_limit; y++) {
+		fill_background(&background_color, output_buffer);
+
+		/* The active planes are composed associatively in z-order. */
+		for (size_t i = 0; i < n_active_planes; i++) {
+			y_pos = get_y_pos(plane[i]->frame_info, y);
+
+			if (!check_limit(plane[i]->frame_info, y_pos))
+				continue;
+
+			vkms_compose_row(stage_buffer, plane[i], y_pos);
+			pre_mul_alpha_blend(plane[i]->frame_info, stage_buffer,
+					    output_buffer);
+		}
+
+		apply_lut(crtc_state, output_buffer);
+
+		*crc32 = crc32_le(*crc32, (void *)output_buffer->pixels, row_size);
+
+		if (wb)
+			vkms_writeback_row(wb, output_buffer, y_pos);
+	}
+}
+
+static int check_format_funcs(struct vkms_crtc_state *crtc_state,
+			      struct vkms_writeback_job *active_wb)
+{
+	struct vkms_plane_state **planes = crtc_state->active_planes;
+	u32 n_active_planes = crtc_state->num_active_planes;
+
+	for (size_t i = 0; i < n_active_planes; i++)
+		if (!planes[i]->pixel_read)
+			return -1;
+
+	if (active_wb && !active_wb->pixel_write)
+		return -1;
+
+	return 0;
+}
+
+static int check_iosys_map(struct vkms_crtc_state *crtc_state)
+{
+	struct vkms_plane_state **plane_state = crtc_state->active_planes;
+	u32 n_active_planes = crtc_state->num_active_planes;
+
+	for (size_t i = 0; i < n_active_planes; i++)
+		if (iosys_map_is_null(&plane_state[i]->frame_info->map[0]))
+			return -1;
+
+	return 0;
+}
+
+static int compose_active_planes(struct vkms_writeback_job *active_wb,
+				 struct vkms_crtc_state *crtc_state,
+				 u32 *crc32)
+{
+	size_t line_width, pixel_size = sizeof(struct pixel_argb_u16);
+	struct line_buffer output_buffer, stage_buffer;
+	int ret = 0;
+
+	/*
+	 * This check exists so we can call `crc32_le` for the entire line
+	 * instead doing it for each channel of each pixel in case
+	 * `struct `pixel_argb_u16` had any gap added by the compiler
+	 * between the struct fields.
+	 */
+	static_assert(sizeof(struct pixel_argb_u16) == 8);
+
+	if (WARN_ON(check_iosys_map(crtc_state)))
+		return -EINVAL;
+
+	if (WARN_ON(check_format_funcs(crtc_state, active_wb)))
+		return -EINVAL;
+
+	line_width = crtc_state->base.crtc->mode.hdisplay;
+	stage_buffer.n_pixels = line_width;
+	output_buffer.n_pixels = line_width;
+
+	stage_buffer.pixels = kvmalloc(line_width * pixel_size, GFP_KERNEL);
+	if (!stage_buffer.pixels) {
+		DRM_ERROR("Cannot allocate memory for the output line buffer");
+		return -ENOMEM;
+	}
+
+	output_buffer.pixels = kvmalloc(line_width * pixel_size, GFP_KERNEL);
+	if (!output_buffer.pixels) {
+		DRM_ERROR("Cannot allocate memory for intermediate line buffer");
+		ret = -ENOMEM;
+		goto free_stage_buffer;
+	}
+
+	blend(active_wb, crtc_state, crc32, &stage_buffer,
+	      &output_buffer, line_width * pixel_size);
+
+	kvfree(output_buffer.pixels);
+free_stage_buffer:
+	kvfree(stage_buffer.pixels);
+
+	return ret;
+}
+
+/**
+ * vkms_composer_worker - ordered work_struct to compute CRC
+ *
+ * @work: work_struct
+ *
+ * Work handler for composing and computing CRCs. work_struct scheduled in
+ * an ordered workqueue that's periodically scheduled to run by
+ * vkms_vblank_simulate() and flushed at vkms_atomic_commit_tail().
+ */
+void vkms_composer_worker(struct work_struct *work)
+{
+	struct vkms_crtc_state *crtc_state = container_of(work,
+						struct vkms_crtc_state,
+						composer_work);
+	struct drm_crtc *crtc = crtc_state->base.crtc;
+	struct vkms_writeback_job *active_wb = crtc_state->active_writeback;
+	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
+	bool crc_pending, wb_pending;
+	u64 frame_start, frame_end;
+	u32 crc32 = 0;
+	int ret;
+
+	spin_lock_irq(&out->composer_lock);
+	frame_start = crtc_state->frame_start;
+	frame_end = crtc_state->frame_end;
+	crc_pending = crtc_state->crc_pending;
+	wb_pending = crtc_state->wb_pending;
+	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);
+
+	/*
+	 * We raced with the vblank hrtimer and previous work already computed
+	 * the crc, nothing to do.
+	 */
+	if (!crc_pending)
+		return;
+
+	if (wb_pending)
+		ret = compose_active_planes(active_wb, crtc_state, &crc32);
+	else
+		ret = compose_active_planes(NULL, crtc_state, &crc32);
+
+	if (ret)
+		return;
+
+	if (wb_pending) {
+		drm_writeback_signal_completion(&out->wb_connector, 0);
+		spin_lock_irq(&out->composer_lock);
+		crtc_state->wb_pending = false;
+		spin_unlock_irq(&out->composer_lock);
+	}
+
+	/*
+	 * The worker can fall behind the vblank hrtimer, make sure we catch up.
+	 */
+	while (frame_start <= frame_end)
+		drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);
+}
+
+static const char * const pipe_crc_sources[] = {"auto"};
+
+const char *const *vkms_get_crc_sources(struct drm_crtc *crtc,
+					size_t *count)
+{
+	*count = ARRAY_SIZE(pipe_crc_sources);
+	return pipe_crc_sources;
+}
+
+static int vkms_crc_parse_source(const char *src_name, bool *enabled)
+{
+	int ret = 0;
+
+	if (!src_name) {
+		*enabled = false;
+	} else if (strcmp(src_name, "auto") == 0) {
+		*enabled = true;
+	} else {
+		*enabled = false;
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name,
+			   size_t *values_cnt)
+{
+	bool enabled;
+
+	if (vkms_crc_parse_source(src_name, &enabled) < 0) {
+		DRM_DEBUG_DRIVER("unknown source %s\n", src_name);
+		return -EINVAL;
+	}
+
+	*values_cnt = 1;
+
+	return 0;
+}
+
+void vkms_set_composer(struct vkms_output *out, bool enabled)
+{
+	bool old_enabled;
+
+	if (enabled)
+		drm_crtc_vblank_get(&out->crtc);
+
+	spin_lock_irq(&out->lock);
+	old_enabled = out->composer_enabled;
+	out->composer_enabled = enabled;
+	spin_unlock_irq(&out->lock);
+
+	if (old_enabled)
+		drm_crtc_vblank_put(&out->crtc);
+}
+
+int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
+{
+	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
+	bool enabled = false;
+	int ret = 0;
+
+	ret = vkms_crc_parse_source(src_name, &enabled);
+
+	vkms_set_composer(out, enabled);
+
+	return ret;
+}