Hi Louis,
On 07/10/24 13:10, 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@xxxxxxxxx/
[2]: commit 322d716a3e8a ("drm/vkms: isolate pixel conversion
functionality")
https://lore.kernel.org/all/20230418130525.128733-2-mcanal@xxxxxxxxxx/
[3]: https://lore.kernel.org/igt-dev/20240313-new_rotation-v2-0-6230fd5cae59@xxxxxxxxxxx/
[4]: https://lore.kernel.org/all/20240422-kms_fb_stress-dev-v5-0-0c577163dc88@xxxxxxxxxx/
Signed-off-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
Acked-by: Pekka Paalanen <pekka.paalanen@xxxxxxxxxxxxx>
# Conflicts:
# drivers/gpu/drm/vkms/vkms_composer.c
---
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(-)
[...]
-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@xxxxxxxxxx/
*/
-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;
Why are you converting u8* to u8*? There are repetitions of this pattern
in this patch.
+ *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));
If you won't use rotated anymore, delete it from the struct.
Best Regards,
- Maíra
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,
