Re-introduce a line-by-line composition algorithm for each pixel format.
This allows more performance by not requiring an indirection per pixel
read. This patch is focused on readability of the code.
Line-by-line composition was introduced by [1] but rewritten back to
pixel-by-pixel algorithm in [2]. At this time, nobody noticed the impact
on performance, and it was merged.
This patch is almost a revert of [2], but in addition efforts have been
made to increase readability and maintainability of the rotation handling.
The blend function is now divided in two parts:
- Transformation of coordinates from the output referential to the source
referential
- Line conversion and blending
Most of the complexity of the rotation management is avoided by using
drm_rect_* helpers. The remaining complexity is around the clipping, to
avoid reading/writing outside source/destination buffers.
The pixel conversion is now done line-by-line, so the read_pixel_t was
replaced with read_pixel_line_t callback. This way the indirection is only
required once per line and per plane, instead of once per pixel and per
plane.
The read_line_t callbacks are very similar for most pixel format, but it
is required to avoid performance impact. Some helpers for color
conversion were introduced to avoid code repetition:
- *_to_argb_u16: perform colors conversion. They should be inlined by the
compiler, and they are used to avoid repetition between multiple variants
of the same format (argb/xrgb and maybe in the future for formats like
bgr formats).
This new algorithm was tested with:
- kms_plane (for color conversions)
- kms_rotation_crc (for rotations of planes)
- kms_cursor_crc (for translations of planes)
- kms_rotation (for all rotations and formats combinations) [3]
The performance gain was mesured with kms_fb_stress [4] with some
modification to fix the writeback format.
The performance improvement is around 5 to 10%.
[1]: commit 8ba1648567e2 ("drm: vkms: Refactor the plane composer to accept
new formats")
https://lore.kernel.org/all/20220905190811.25024-7-igormtorrente@gmail.com/
[2]: commit 322d716a3e8a ("drm/vkms: isolate pixel conversion
functionality")
https://lore.kernel.org/all/20230418130525.128733-2-mcanal@igalia.com/
[3]: https://lore.kernel.org/igt-dev/20240313-new_rotation-v2-0-6230fd5cae59@bootlin.com/
[4]: https://lore.kernel.org/all/20240422-kms_fb_stress-dev-v5-0-0c577163dc88@riseup.net/
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
---
drivers/gpu/drm/vkms/vkms_composer.c | 234 ++++++++++++++++++++++++++++-------
drivers/gpu/drm/vkms/vkms_drv.h | 28 +++--
drivers/gpu/drm/vkms/vkms_formats.c | 224 ++++++++++++++++++++-------------
drivers/gpu/drm/vkms/vkms_formats.h | 2 +-
drivers/gpu/drm/vkms/vkms_plane.c | 5 +-
5 files changed, 344 insertions(+), 149 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index 4ebeaf58fa75..76d4aa8a0ef6 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -29,8 +29,8 @@ static u16 pre_mul_blend_channel(u16 src, u16 dst, u16 alpha)
* @x_start: The start offset
* @pixel_count: The number of pixels to blend
*
- * The pixels 0..@pixel_count in stage_buffer are blended at @x_start..@x_start+@pixel_count in
- * output_buffer.
+ * The pixels @x_start..@x_start+@pixel_count in stage_buffer are blended at
+ * @x_start..@x_start+@pixel_count in output_buffer.
*
* The current DRM assumption is that pixel color values have been already
* pre-multiplied with the alpha channel values. See more
@@ -41,7 +41,7 @@ static void pre_mul_alpha_blend(const struct line_buffer *stage_buffer,
struct line_buffer *output_buffer, int x_start, int pixel_count)
{
struct pixel_argb_u16 *out = &output_buffer->pixels[x_start];
- const struct pixel_argb_u16 *in = stage_buffer->pixels;
+ const struct pixel_argb_u16 *in = &stage_buffer->pixels[x_start];
for (int i = 0; i < pixel_count; i++) {
out[i].a = (u16)0xffff;
@@ -51,33 +51,6 @@ static void pre_mul_alpha_blend(const struct line_buffer *stage_buffer,
}
}
-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)
@@ -203,6 +176,182 @@ static enum pixel_read_direction direction_for_rotation(unsigned int rotation)
return READ_LEFT_TO_RIGHT;
}
+/**
+ * clamp_line_coordinates() - Compute and clamp the coordinate to read and write during the blend
+ * process.
+ *
+ * @direction: direction of the reading
+ * @current_plane: current plane blended
+ * @src_line: source line of the reading. Only the top-left coordinate is used. This rectangle
+ * must be rotated and have a shape of 1*pixel_count if @direction is vertical and a shape of
+ * pixel_count*1 if @direction is horizontal.
+ * @src_x_start: x start coordinate for the line reading
+ * @src_y_start: y start coordinate for the line reading
+ * @dst_x_start: x coordinate to blend the read line
+ * @pixel_count: number of pixels to blend
+ *
+ * This function is mainly a safety net to avoid reading outside the source buffer. As the
+ * userspace should never ask to read outside the source plane, all the cases covered here should
+ * be dead code.
+ */
+static void clamp_line_coordinates(enum pixel_read_direction direction,
+ const struct vkms_plane_state *current_plane,
+ const struct drm_rect *src_line, int *src_x_start,
+ int *src_y_start, int *dst_x_start, int *pixel_count)
+{
+ /* By default the start points are correct */
+ *src_x_start = src_line->x1;
+ *src_y_start = src_line->y1;
+ *dst_x_start = current_plane->frame_info->dst.x1;
+
+ /* Get the correct number of pixel to blend, it depends of the direction */
+ switch (direction) {
+ case READ_LEFT_TO_RIGHT:
+ case READ_RIGHT_TO_LEFT:
+ *pixel_count = drm_rect_width(src_line);
+ break;
+ case READ_BOTTOM_TO_TOP:
+ case READ_TOP_TO_BOTTOM:
+ *pixel_count = drm_rect_height(src_line);
+ break;
+ }
+
+ /*
+ * Clamp the coordinates to avoid reading outside the buffer
+ *
+ * This is mainly a security to avoid reading outside the buffer, the userspace should
+ * never request to read outside the source buffer.
+ */
+ switch (direction) {
+ case READ_LEFT_TO_RIGHT:
+ case READ_RIGHT_TO_LEFT:
+ if (*src_x_start < 0) {
+ *pixel_count += *src_x_start;
+ *dst_x_start -= *src_x_start;
+ *src_x_start = 0;
+ }
+ if (*src_x_start + *pixel_count > current_plane->frame_info->fb->width)
+ *pixel_count = max(0, (int)current_plane->frame_info->fb->width -
+ *src_x_start);
+ break;
+ case READ_BOTTOM_TO_TOP:
+ case READ_TOP_TO_BOTTOM:
+ if (*src_y_start < 0) {
+ *pixel_count += *src_y_start;
+ *dst_x_start -= *src_y_start;
+ *src_y_start = 0;
+ }
+ if (*src_y_start + *pixel_count > current_plane->frame_info->fb->height)
+ *pixel_count = max(0, (int)current_plane->frame_info->fb->height -
+ *src_y_start);
+ break;
+ }
+}
+
+/**
+ * blend_line() - Blend a line from a plane to the output buffer
+ *
+ * @current_plane: current plane to work on
+ * @y: line to write in the output buffer
+ * @crtc_x_limit: width of the output buffer
+ * @stage_buffer: temporary buffer to convert the pixel line from the source buffer
+ * @output_buffer: buffer to blend the read line into.
+ */
+static void blend_line(struct vkms_plane_state *current_plane, int y,
+ int crtc_x_limit, struct line_buffer *stage_buffer,
+ struct line_buffer *output_buffer)
+{
+ int src_x_start, src_y_start, dst_x_start, pixel_count;
+ struct drm_rect dst_line, tmp_src, src_line;
+
+ /* Avoid rendering useless lines */
+ if (y < current_plane->frame_info->dst.y1 ||
+ y >= current_plane->frame_info->dst.y2)
+ return;
+
+ /*
+ * dst_line is the line to copy. The initial coordinates are inside the
+ * destination framebuffer, and then drm_rect_* helpers are used to
+ * compute the correct position into the source framebuffer.
+ */
+ dst_line = DRM_RECT_INIT(current_plane->frame_info->dst.x1, y,
+ drm_rect_width(¤t_plane->frame_info->dst),
+ 1);
+
+ drm_rect_fp_to_int(&tmp_src, ¤t_plane->frame_info->src);
+
+ /*
+ * [1]: Clamping src_line to the crtc_x_limit to avoid writing outside of
+ * the destination buffer
+ */
+ dst_line.x1 = max_t(int, dst_line.x1, 0);
+ dst_line.x2 = min_t(int, dst_line.x2, crtc_x_limit);
+ /* The destination is completely outside of the crtc. */
+ if (dst_line.x2 <= dst_line.x1)
+ return;
+
+ src_line = dst_line;
+
+ /*
+ * Transform the coordinate x/y from the crtc to coordinates into
+ * coordinates for the src buffer.
+ *
+ * - Cancel the offset of the dst buffer.
+ * - Invert the rotation. This assumes that
+ * dst = drm_rect_rotate(src, rotation) (dst and src have the
+ * same size, but can be rotated).
+ * - Apply the offset of the source rectangle to the coordinate.
+ */
+ drm_rect_translate(&src_line, -current_plane->frame_info->dst.x1,
+ -current_plane->frame_info->dst.y1);
+ drm_rect_rotate_inv(&src_line, drm_rect_width(&tmp_src),
+ drm_rect_height(&tmp_src),
+ current_plane->frame_info->rotation);
+ drm_rect_translate(&src_line, tmp_src.x1, tmp_src.y1);
+
+ /* Get the correct reading direction in the source buffer. */
+
+ enum pixel_read_direction direction =
+ direction_for_rotation(current_plane->frame_info->rotation);
+
+ /* [2]: Compute and clamp the number of pixel to read */
+ clamp_line_coordinates(direction, current_plane, &src_line, &src_x_start, &src_y_start,
+ &dst_x_start, &pixel_count);
+
+ if (pixel_count <= 0) {
+ /* Nothing to read, so avoid multiple function calls */
+ return;
+ }
+
+ /*
+ * Modify the starting point to take in account the rotation
+ *
+ * src_line is the top-left corner, so when reading READ_RIGHT_TO_LEFT or
+ * READ_BOTTOM_TO_TOP, it must be changed to the top-right/bottom-left
+ * corner.
+ */
+ if (direction == READ_RIGHT_TO_LEFT) {
+ // src_x_start is now the right point
+ src_x_start += pixel_count - 1;
+ } else if (direction == READ_BOTTOM_TO_TOP) {
+ // src_y_start is now the bottom point
+ src_y_start += pixel_count - 1;
+ }
+
+ /*
+ * Perform the conversion and the blending
+ *
+ * Here we know that the read line (x_start, y_start, pixel_count) is
+ * inside the source buffer [2] and we don't write outside the stage
+ * buffer [1].
+ */
+ current_plane->pixel_read_line(current_plane, src_x_start, src_y_start, direction,
+ pixel_count, &stage_buffer->pixels[dst_x_start]);
+
+ pre_mul_alpha_blend(stage_buffer, output_buffer,
+ dst_x_start, pixel_count);
+}
+
/**
* blend - blend the pixels from all planes and compute crc
* @wb: The writeback frame buffer metadata
@@ -223,34 +372,25 @@ static void blend(struct vkms_writeback_job *wb,
{
struct vkms_plane_state **plane = crtc_state->active_planes;
u32 n_active_planes = crtc_state->num_active_planes;
- int y_pos, x_dst, pixel_count;
const struct pixel_argb_u16 background_color = { .a = 0xffff };
- size_t crtc_y_limit = crtc_state->base.crtc->mode.vdisplay;
+ int crtc_y_limit = crtc_state->base.crtc->mode.vdisplay;
+ int crtc_x_limit = crtc_state->base.crtc->mode.hdisplay;
/*
* The planes are composed line-by-line to avoid heavy memory usage. It is a necessary
* complexity to avoid poor blending performance.
*
- * The function vkms_compose_row() is used to read a line, pixel-by-pixel, into the staging
- * buffer.
+ * The function pixel_read_line callback is used to read a line, using an efficient
+ * algorithm for a specific format, into the staging buffer.
*/
- for (size_t y = 0; y < crtc_y_limit; y++) {
+ for (int 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++) {
- x_dst = plane[i]->frame_info->dst.x1;
- pixel_count = min_t(int, drm_rect_width(&plane[i]->frame_info->dst),
- (int)stage_buffer->n_pixels);
- 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(stage_buffer, output_buffer, x_dst, pixel_count);
+ blend_line(plane[i], y, crtc_x_limit, stage_buffer, output_buffer);
}
apply_lut(crtc_state, output_buffer);
@@ -258,7 +398,7 @@ static void blend(struct vkms_writeback_job *wb,
*crc32 = crc32_le(*crc32, (void *)output_buffer->pixels, row_size);
if (wb)
- vkms_writeback_row(wb, output_buffer, y_pos);
+ vkms_writeback_row(wb, output_buffer, y);
}
}
@@ -269,7 +409,7 @@ static int check_format_funcs(struct vkms_crtc_state *crtc_state,
u32 n_active_planes = crtc_state->num_active_planes;
for (size_t i = 0; i < n_active_planes; i++)
- if (!planes[i]->pixel_read)
+ if (!planes[i]->pixel_read_line)
return -1;
if (active_wb && !active_wb->pixel_write)
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index b3e53b607039..e91cfbf3ce0a 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -39,7 +39,6 @@
struct vkms_frame_info {
struct drm_framebuffer *fb;
struct drm_rect src, dst;
- struct drm_rect rotated;
struct iosys_map map[DRM_FORMAT_MAX_PLANES];
unsigned int rotation;
};
@@ -80,26 +79,38 @@ enum pixel_read_direction {
READ_LEFT_TO_RIGHT
};
+struct vkms_plane_state;
+
/**
- * typedef pixel_read_t - These functions are used to read a pixel in the source frame,
+ * typedef pixel_read_line_t - These functions are used to read a pixel line in the source frame,
* convert it to `struct pixel_argb_u16` and write it to @out_pixel.
*
- * @in_pixel: pointer to the pixel to read
- * @out_pixel: pointer to write the converted pixel
+ * @plane: plane used as source for the pixel value
+ * @x_start: X (width) coordinate of the first pixel to copy. The caller must ensure that x_start
+ * is non-negative and smaller than @plane->frame_info->fb->width.
+ * @y_start: Y (height) coordinate of the first pixel to copy. The caller must ensure that y_start
+ * is non-negative and smaller than @plane->frame_info->fb->height.
+ * @direction: direction to use for the copy, starting at @x_start/@y_start
+ * @count: number of pixels to copy
+ * @out_pixel: pointer where to write the pixel values. They will be written from @out_pixel[0]
+ * (included) to @out_pixel[@count] (excluded). The caller must ensure that out_pixel have a
+ * length of at least @count.
*/
-typedef void (*pixel_read_t)(const u8 *in_pixel, struct pixel_argb_u16 *out_pixel);
+typedef void (*pixel_read_line_t)(const struct vkms_plane_state *plane, int x_start,
+ int y_start, enum pixel_read_direction direction, int count,
+ struct pixel_argb_u16 out_pixel[]);
/**
* struct vkms_plane_state - Driver specific plane state
* @base: base plane state
* @frame_info: data required for composing computation
- * @pixel_read: function to read a pixel in this plane. The creator of a struct vkms_plane_state
- * must ensure that this pointer is valid
+ * @pixel_read_line: function to read a pixel line in this plane. The creator of a
+ * struct vkms_plane_state must ensure that this pointer is valid
*/
struct vkms_plane_state {
struct drm_shadow_plane_state base;
struct vkms_frame_info *frame_info;
- pixel_read_t pixel_read;
+ pixel_read_line_t pixel_read_line;
};
struct vkms_plane {
@@ -265,7 +276,6 @@ int vkms_verify_crc_source(struct drm_crtc *crtc, const char *source_name,
/* Composer Support */
void vkms_composer_worker(struct work_struct *work);
void vkms_set_composer(struct vkms_output *out, bool enabled);
-void vkms_compose_row(struct line_buffer *stage_buffer, struct vkms_plane_state *plane, int y);
void vkms_writeback_row(struct vkms_writeback_job *wb, const struct line_buffer *src_buffer, int y);
/* Writeback */
diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
index d0e7dfc1f0d3..0f6678420a11 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.c
+++ b/drivers/gpu/drm/vkms/vkms_formats.c
@@ -140,83 +140,51 @@ static void packed_pixels_addr_1x1(const struct vkms_frame_info *frame_info,
*addr = (u8 *)frame_info->map[0].vaddr + offset;
}
-static void *get_packed_src_addr(const struct vkms_frame_info *frame_info, int y,
- int plane_index)
-{
- int x_src = frame_info->src.x1 >> 16;
- int y_src = y - frame_info->rotated.y1 + (frame_info->src.y1 >> 16);
- u8 *addr;
- int rem_x, rem_y;
-
- WARN_ONCE(drm_format_info_block_width(frame_info->fb->format, plane_index) != 1,
- "%s() only support formats with block_w == 1", __func__);
- WARN_ONCE(drm_format_info_block_height(frame_info->fb->format, plane_index) != 1,
- "%s() only support formats with block_h == 1", __func__);
-
- packed_pixels_addr(frame_info, x_src, y_src, plane_index, &addr, &rem_x, &rem_y);
-
- return addr;
-}
-
-static int get_x_position(const struct vkms_frame_info *frame_info, int limit, int x)
-{
- if (frame_info->rotation & (DRM_MODE_REFLECT_X | DRM_MODE_ROTATE_270))
- return limit - x - 1;
- return x;
-}
-
/*
- * The following functions take pixel data from the buffer and convert them to the format
- * ARGB16161616 in @out_pixel.
+ * The following functions take pixel data (a, r, g, b, pixel, ...) and convert them to
+ * &struct pixel_argb_u16
*
- * They are used in the vkms_compose_row() function to handle multiple formats.
+ * They are used in the `read_line`s functions to avoid duplicate work for some pixel formats.
*/
-static void ARGB8888_to_argb_u16(const u8 *in_pixel, struct pixel_argb_u16 *out_pixel)
+static struct pixel_argb_u16 argb_u16_from_u8888(u8 a, u8 r, u8 g, u8 b)
{
+ struct pixel_argb_u16 out_pixel;
/*
* The 257 is the "conversion ratio". This number is obtained by the
* (2^16 - 1) / (2^8 - 1) division. Which, in this case, tries to get
* the best color value in a pixel format with more possibilities.
* A similar idea applies to others RGB color conversions.
*/
- out_pixel->a = (u16)in_pixel[3] * 257;
- out_pixel->r = (u16)in_pixel[2] * 257;
- out_pixel->g = (u16)in_pixel[1] * 257;
- out_pixel->b = (u16)in_pixel[0] * 257;
-}
+ out_pixel.a = (u16)a * 257;
+ out_pixel.r = (u16)r * 257;
+ out_pixel.g = (u16)g * 257;
+ out_pixel.b = (u16)b * 257;
-static void XRGB8888_to_argb_u16(const u8 *in_pixel, struct pixel_argb_u16 *out_pixel)
-{
- out_pixel->a = (u16)0xffff;
- out_pixel->r = (u16)in_pixel[2] * 257;
- out_pixel->g = (u16)in_pixel[1] * 257;
- out_pixel->b = (u16)in_pixel[0] * 257;
+ return out_pixel;
}
-static void ARGB16161616_to_argb_u16(const u8 *in_pixel, struct pixel_argb_u16 *out_pixel)
+static struct pixel_argb_u16 argb_u16_from_u16161616(u16 a, u16 r, u16 g, u16 b)
{
- __le16 *pixel = (__le16 *)in_pixel;
+ struct pixel_argb_u16 out_pixel;
+
+ out_pixel.a = a;
+ out_pixel.r = r;
+ out_pixel.g = g;
+ out_pixel.b = b;
- out_pixel->a = le16_to_cpu(pixel[3]);
- out_pixel->r = le16_to_cpu(pixel[2]);
- out_pixel->g = le16_to_cpu(pixel[1]);
- out_pixel->b = le16_to_cpu(pixel[0]);
+ return out_pixel;
}
-static void XRGB16161616_to_argb_u16(const u8 *in_pixel, struct pixel_argb_u16 *out_pixel)
+static struct pixel_argb_u16 argb_u16_from_le16161616(__le16 a, __le16 r, __le16 g, __le16 b)
{
- __le16 *pixel = (__le16 *)in_pixel;
-
- out_pixel->a = (u16)0xffff;
- out_pixel->r = le16_to_cpu(pixel[2]);
- out_pixel->g = le16_to_cpu(pixel[1]);
- out_pixel->b = le16_to_cpu(pixel[0]);
+ return argb_u16_from_u16161616(le16_to_cpu(a), le16_to_cpu(r), le16_to_cpu(g),
+ le16_to_cpu(b));
}
-static void RGB565_to_argb_u16(const u8 *in_pixel, struct pixel_argb_u16 *out_pixel)
+static struct pixel_argb_u16 argb_u16_from_RGB565(const __le16 *pixel)
{
- __le16 *pixel = (__le16 *)in_pixel;
+ struct pixel_argb_u16 out_pixel;
s64 fp_rb_ratio = drm_fixp_div(drm_int2fixp(65535), drm_int2fixp(31));
s64 fp_g_ratio = drm_fixp_div(drm_int2fixp(65535), drm_int2fixp(63));
@@ -226,40 +194,120 @@ static void RGB565_to_argb_u16(const u8 *in_pixel, struct pixel_argb_u16 *out_pi
s64 fp_g = drm_int2fixp((rgb_565 >> 5) & 0x3f);
s64 fp_b = drm_int2fixp(rgb_565 & 0x1f);
- out_pixel->a = (u16)0xffff;
- out_pixel->r = drm_fixp2int_round(drm_fixp_mul(fp_r, fp_rb_ratio));
- out_pixel->g = drm_fixp2int_round(drm_fixp_mul(fp_g, fp_g_ratio));
- out_pixel->b = drm_fixp2int_round(drm_fixp_mul(fp_b, fp_rb_ratio));
+ out_pixel.a = (u16)0xffff;
+ out_pixel.r = drm_fixp2int_round(drm_fixp_mul(fp_r, fp_rb_ratio));
+ out_pixel.g = drm_fixp2int_round(drm_fixp_mul(fp_g, fp_g_ratio));
+ out_pixel.b = drm_fixp2int_round(drm_fixp_mul(fp_b, fp_rb_ratio));
+
+ return out_pixel;
}
-/**
- * vkms_compose_row - compose a single row of a plane
- * @stage_buffer: output line with the composed pixels
- * @plane: state of the plane that is being composed
- * @y: y coordinate of the row
+/*
+ * The following functions are read_line function for each pixel format supported by VKMS.
+ *
+ * They read a line starting at the point @x_start,@y_start following the @direction. The result
+ * is stored in @out_pixel and in the format ARGB16161616.
+ *
+ * These functions are very repetitive, but the innermost pixel loops must be kept inside these
+ * functions for performance reasons. Some benchmarking was done in [1] where having the innermost
+ * loop factored out of these functions showed a slowdown by a factor of three.
*
- * This function composes a single row of a plane. It gets the source pixels
- * through the y coordinate (see get_packed_src_addr()) and goes linearly
- * through the source pixel, reading the pixels and converting it to
- * ARGB16161616 (see the pixel_read() callback). For rotate-90 and rotate-270,
- * the source pixels are not traversed linearly. The source pixels are queried
- * on each iteration in order to traverse the pixels vertically.
+ * [1]: https://lore.kernel.org/dri-devel/d258c8dc-78e9-4509-9037-a98f7f33b3a3@riseup.net/
*/
-void vkms_compose_row(struct line_buffer *stage_buffer, struct vkms_plane_state *plane, int y)
+
+static void ARGB8888_read_line(const struct vkms_plane_state *plane, int x_start, int y_start,
+ enum pixel_read_direction direction, int count,
+ struct pixel_argb_u16 out_pixel[])
{
- struct pixel_argb_u16 *out_pixels = stage_buffer->pixels;
- struct vkms_frame_info *frame_info = plane->frame_info;
- u8 *src_pixels = get_packed_src_addr(frame_info, y, 0);
- int limit = min_t(size_t, drm_rect_width(&frame_info->dst), stage_buffer->n_pixels);
+ struct pixel_argb_u16 *end = out_pixel + count;
+ u8 *src_pixels;
+
+ packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
+
+ int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
+
+ while (out_pixel < end) {
+ u8 *px = (u8 *)src_pixels;
+ *out_pixel = argb_u16_from_u8888(px[3], px[2], px[1], px[0]);
+ out_pixel += 1;
+ src_pixels += step;
+ }
+}
+
+static void XRGB8888_read_line(const struct vkms_plane_state *plane, int x_start, int y_start,
+ enum pixel_read_direction direction, int count,
+ struct pixel_argb_u16 out_pixel[])
+{
+ struct pixel_argb_u16 *end = out_pixel + count;
+ u8 *src_pixels;
+
+ packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
+
+ int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
+
+ while (out_pixel < end) {
+ u8 *px = (u8 *)src_pixels;
+ *out_pixel = argb_u16_from_u8888(255, px[2], px[1], px[0]);
+ out_pixel += 1;
+ src_pixels += step;
+ }
+}
+
+static void ARGB16161616_read_line(const struct vkms_plane_state *plane, int x_start,
+ int y_start, enum pixel_read_direction direction, int count,
+ struct pixel_argb_u16 out_pixel[])
+{
+ struct pixel_argb_u16 *end = out_pixel + count;
+ u8 *src_pixels;
+
+ packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
+
+ int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
+
+ while (out_pixel < end) {
+ u16 *px = (u16 *)src_pixels;
+ *out_pixel = argb_u16_from_u16161616(px[3], px[2], px[1], px[0]);
+ out_pixel += 1;
+ src_pixels += step;
+ }
+}
+
+static void XRGB16161616_read_line(const struct vkms_plane_state *plane, int x_start,
+ int y_start, enum pixel_read_direction direction, int count,
+ struct pixel_argb_u16 out_pixel[])
+{
+ struct pixel_argb_u16 *end = out_pixel + count;
+ u8 *src_pixels;
+
+ packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
+
+ int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
+
+ while (out_pixel < end) {
+ __le16 *px = (__le16 *)src_pixels;
+ *out_pixel = argb_u16_from_le16161616(cpu_to_le16(0xFFFF), px[2], px[1], px[0]);
+ out_pixel += 1;
+ src_pixels += step;
+ }
+}
+
+static void RGB565_read_line(const struct vkms_plane_state *plane, int x_start,
+ int y_start, enum pixel_read_direction direction, int count,
+ struct pixel_argb_u16 out_pixel[])
+{
+ struct pixel_argb_u16 *end = out_pixel + count;
+ u8 *src_pixels;
+
+ packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
- for (size_t x = 0; x < limit; x++, src_pixels += frame_info->fb->format->cpp[0]) {
- int x_pos = get_x_position(frame_info, limit, x);
+ int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
- if (drm_rotation_90_or_270(frame_info->rotation))
- src_pixels = get_packed_src_addr(frame_info, x + frame_info->rotated.y1, 0)
- + frame_info->fb->format->cpp[0] * y;
+ while (out_pixel < end) {
+ __le16 *px = (__le16 *)src_pixels;
- plane->pixel_read(src_pixels, &out_pixels[x_pos]);
+ *out_pixel = argb_u16_from_RGB565(px);
+ out_pixel += 1;
+ src_pixels += step;
}
}
@@ -359,25 +407,25 @@ void vkms_writeback_row(struct vkms_writeback_job *wb,
}
/**
- * get_pixel_read_function() - Retrieve the correct read_pixel function for a specific
+ * get_pixel_read_line_function() - Retrieve the correct read_line function for a specific
* format. The returned pointer is NULL for unsupported pixel formats. The caller must ensure that
* the pointer is valid before using it in a vkms_plane_state.
*
* @format: DRM_FORMAT_* value for which to obtain a conversion function (see [drm_fourcc.h])
*/
-pixel_read_t get_pixel_read_function(u32 format)
+pixel_read_line_t get_pixel_read_line_function(u32 format)
{
switch (format) {
case DRM_FORMAT_ARGB8888:
- return &ARGB8888_to_argb_u16;
+ return &ARGB8888_read_line;
case DRM_FORMAT_XRGB8888:
- return &XRGB8888_to_argb_u16;
+ return &XRGB8888_read_line;
case DRM_FORMAT_ARGB16161616:
- return &ARGB16161616_to_argb_u16;
+ return &ARGB16161616_read_line;
case DRM_FORMAT_XRGB16161616:
- return &XRGB16161616_to_argb_u16;
+ return &XRGB16161616_read_line;
case DRM_FORMAT_RGB565:
- return &RGB565_to_argb_u16;
+ return &RGB565_read_line;
default:
/*
* This is a bug in vkms_plane_atomic_check(). All the supported
diff --git a/drivers/gpu/drm/vkms/vkms_formats.h b/drivers/gpu/drm/vkms/vkms_formats.h
index 3ecea4563254..8d2bef95ff79 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.h
+++ b/drivers/gpu/drm/vkms/vkms_formats.h
@@ -5,7 +5,7 @@
#include "vkms_drv.h"
-pixel_read_t get_pixel_read_function(u32 format);
+pixel_read_line_t get_pixel_read_line_function(u32 format);
pixel_write_t get_pixel_write_function(u32 format);
diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
index 10e9b23dab28..8875bed76410 100644
--- a/drivers/gpu/drm/vkms/vkms_plane.c
+++ b/drivers/gpu/drm/vkms/vkms_plane.c
@@ -112,7 +112,6 @@ static void vkms_plane_atomic_update(struct drm_plane *plane,
frame_info = vkms_plane_state->frame_info;
memcpy(&frame_info->src, &new_state->src, sizeof(struct drm_rect));
memcpy(&frame_info->dst, &new_state->dst, sizeof(struct drm_rect));
- memcpy(&frame_info->rotated, &new_state->dst, sizeof(struct drm_rect));
frame_info->fb = fb;
memcpy(&frame_info->map, &shadow_plane_state->data, sizeof(frame_info->map));
drm_framebuffer_get(frame_info->fb);
@@ -122,10 +121,8 @@ static void vkms_plane_atomic_update(struct drm_plane *plane,
DRM_MODE_REFLECT_X |
DRM_MODE_REFLECT_Y);
- drm_rect_rotate(&frame_info->rotated, drm_rect_width(&frame_info->rotated),
- drm_rect_height(&frame_info->rotated), frame_info->rotation);
- vkms_plane_state->pixel_read = get_pixel_read_function(fmt);
+ vkms_plane_state->pixel_read_line = get_pixel_read_line_function(fmt);
}
static int vkms_plane_atomic_check(struct drm_plane *plane,
--
2.46.2
On 9/30/24 8:31 AM, Louis Chauvet wrote:
> Re-introduce a line-by-line composition algorithm for each pixel format.
> This allows more performance by not requiring an indirection per pixel
> read. This patch is focused on readability of the code.
>
> Line-by-line composition was introduced by [1] but rewritten back to
> pixel-by-pixel algorithm in [2]. At this time, nobody noticed the impact
> on performance, and it was merged.
>
> This patch is almost a revert of [2], but in addition efforts have been
> made to increase readability and maintainability of the rotation handling.
> The blend function is now divided in two parts:
> - Transformation of coordinates from the output referential to the source
> referential
> - Line conversion and blending
>
> Most of the complexity of the rotation management is avoided by using
> drm_rect_* helpers. The remaining complexity is around the clipping, to
> avoid reading/writing outside source/destination buffers.
>
> The pixel conversion is now done line-by-line, so the read_pixel_t was
> replaced with read_pixel_line_t callback. This way the indirection is only
> required once per line and per plane, instead of once per pixel and per
> plane.
>
> The read_line_t callbacks are very similar for most pixel format, but it
> is required to avoid performance impact. Some helpers for color
> conversion were introduced to avoid code repetition:
> - *_to_argb_u16: perform colors conversion. They should be inlined by the
> compiler, and they are used to avoid repetition between multiple variants
> of the same format (argb/xrgb and maybe in the future for formats like
> bgr formats).
>
> This new algorithm was tested with:
> - kms_plane (for color conversions)
> - kms_rotation_crc (for rotations of planes)
> - kms_cursor_crc (for translations of planes)
> - kms_rotation (for all rotations and formats combinations) [3]
> The performance gain was mesured with kms_fb_stress [4] with some
> modification to fix the writeback format.
>
> The performance improvement is around 5 to 10%.
>
> [1]: commit 8ba1648567e2 ("drm: vkms: Refactor the plane composer to accept
> new formats")
> https://lore.kernel.org/all/20220905190811.25024-7-igormtorrente@gmail.com/
> [2]: commit 322d716a3e8a ("drm/vkms: isolate pixel conversion
> functionality")
> https://lore.kernel.org/all/20230418130525.128733-2-mcanal@igalia.com/
> [3]: https://lore.kernel.org/igt-dev/20240313-new_rotation-v2-0-6230fd5cae59@bootlin.com/
> [4]: https://lore.kernel.org/all/20240422-kms_fb_stress-dev-v5-0-0c577163dc88@riseup.net/
>
> Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
> Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
> ---
> drivers/gpu/drm/vkms/vkms_composer.c | 234 ++++++++++++++++++++++++++++-------
> drivers/gpu/drm/vkms/vkms_drv.h | 28 +++--
> drivers/gpu/drm/vkms/vkms_formats.c | 224 ++++++++++++++++++++-------------
> drivers/gpu/drm/vkms/vkms_formats.h | 2 +-
> drivers/gpu/drm/vkms/vkms_plane.c | 5 +-
> 5 files changed, 344 insertions(+), 149 deletions(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> index 4ebeaf58fa75..76d4aa8a0ef6 100644
> --- a/drivers/gpu/drm/vkms/vkms_composer.c
> +++ b/drivers/gpu/drm/vkms/vkms_composer.c
> @@ -29,8 +29,8 @@ static u16 pre_mul_blend_channel(u16 src, u16 dst, u16 alpha)
> * @x_start: The start offset
> * @pixel_count: The number of pixels to blend
> *
> - * The pixels 0..@pixel_count in stage_buffer are blended at @x_start..@x_start+@pixel_count in
> - * output_buffer.
> + * The pixels @x_start..@x_start+@pixel_count in stage_buffer are blended at
> + * @x_start..@x_start+@pixel_count in output_buffer.
with "- 1" somewhere?
> *
> * The current DRM assumption is that pixel color values have been already
> * pre-multiplied with the alpha channel values. See more
> @@ -41,7 +41,7 @@ static void pre_mul_alpha_blend(const struct line_buffer *stage_buffer,
> struct line_buffer *output_buffer, int x_start, int pixel_count)
> {
> struct pixel_argb_u16 *out = &output_buffer->pixels[x_start];
> - const struct pixel_argb_u16 *in = stage_buffer->pixels;
> + const struct pixel_argb_u16 *in = &stage_buffer->pixels[x_start];
>
> for (int i = 0; i < pixel_count; i++) {
> out[i].a = (u16)0xffff;
> @@ -51,33 +51,6 @@ static void pre_mul_alpha_blend(const struct line_buffer *stage_buffer,
> }
> }
>
> -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)
> @@ -203,6 +176,182 @@ static enum pixel_read_direction direction_for_rotation(unsigned int rotation)
> return READ_LEFT_TO_RIGHT;
> }
>
> +/**
> + * clamp_line_coordinates() - Compute and clamp the coordinate to read and write during the blend
> + * process.
> + *
> + * @direction: direction of the reading
> + * @current_plane: current plane blended
> + * @src_line: source line of the reading. Only the top-left coordinate is used. This rectangle
> + * must be rotated and have a shape of 1*pixel_count if @direction is vertical and a shape of
> + * pixel_count*1 if @direction is horizontal.
> + * @src_x_start: x start coordinate for the line reading
> + * @src_y_start: y start coordinate for the line reading
> + * @dst_x_start: x coordinate to blend the read line
> + * @pixel_count: number of pixels to blend
> + *
> + * This function is mainly a safety net to avoid reading outside the source buffer. As the
> + * userspace should never ask to read outside the source plane, all the cases covered here should
> + * be dead code.
> + */
> +static void clamp_line_coordinates(enum pixel_read_direction direction,
> + const struct vkms_plane_state *current_plane,
> + const struct drm_rect *src_line, int *src_x_start,
> + int *src_y_start, int *dst_x_start, int *pixel_count)
> +{
> + /* By default the start points are correct */
> + *src_x_start = src_line->x1;
> + *src_y_start = src_line->y1;
> + *dst_x_start = current_plane->frame_info->dst.x1;
> +
> + /* Get the correct number of pixel to blend, it depends of the direction */
> + switch (direction) {
> + case READ_LEFT_TO_RIGHT:
> + case READ_RIGHT_TO_LEFT:
> + *pixel_count = drm_rect_width(src_line);
> + break;
> + case READ_BOTTOM_TO_TOP:
> + case READ_TOP_TO_BOTTOM:
> + *pixel_count = drm_rect_height(src_line);
> + break;
> + }
> +
> + /*
> + * Clamp the coordinates to avoid reading outside the buffer
> + *
> + * This is mainly a security to avoid reading outside the buffer, the userspace should
a security check to avoid
> + * never request to read outside the source buffer.
> + */
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