The pixel_read_direction enum is useful to describe the reading direction in a plane. It avoids using the rotation property of DRM, which not practical to know the direction of reading. This patch also introduce two helpers, one to compute the pixel_read_direction from the DRM rotation property, and one to compute the step, in byte, between two successive pixel in a specific direction.
Signed-off-by: Louis Chauvet <louis.chau...@bootlin.com> --- drivers/gpu/drm/vkms/vkms_composer.c | 46 ++++++++++++++++++++++++++++++++++++ drivers/gpu/drm/vkms/vkms_drv.h | 11 +++++++++ drivers/gpu/drm/vkms/vkms_formats.c | 30 +++++++++++++++++++++++ 3 files changed, 87 insertions(+) diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c index 45b111c74884..fb4967a00398 100644 --- a/drivers/gpu/drm/vkms/vkms_composer.c +++ b/drivers/gpu/drm/vkms/vkms_composer.c @@ -159,6 +159,52 @@ static void apply_lut(const struct vkms_crtc_state *crtc_state, struct line_buff } } +/** + * direction_for_rotation() - Get the correct reading direction for a given rotation + * + * @rotation: Rotation to analyze. It correspond the field @frame_info.rotation. + * + * This function will use the @rotation setting of a source plane to compute the reading + * direction in this plane which correspond to a "left to right writing" in the CRTC. + * For example, if the buffer is reflected on X axis, the pixel must be read from right to left + * to be written from left to right on the CRTC. + */ +static enum pixel_read_direction direction_for_rotation(unsigned int rotation) +{ + struct drm_rect tmp_a, tmp_b; + int x, y; + + /* + + * Points A and B are depicted as zero-size rectangles on the CRTC. + * The CRTC writing direction is from A to B. The plane reading direction + * is discovered by inverse-transforming A and B. + * The reading direction is computed by rotating the vector AB (top-left to top-right) in a + * 1x1 square. + */ + + tmp_a = DRM_RECT_INIT(0, 0, 0, 0); + tmp_b = DRM_RECT_INIT(1, 0, 0, 0); + drm_rect_rotate_inv(&tmp_a, 1, 1, rotation); + drm_rect_rotate_inv(&tmp_b, 1, 1, rotation); + + x = tmp_b.x1 - tmp_a.x1; + y = tmp_b.y1 - tmp_a.y1; + + if (x == 1 && y == 0) + return READ_LEFT_TO_RIGHT; + else if (x == -1 && y == 0) + return READ_RIGHT_TO_LEFT; + else if (y == 1 && x == 0) + return READ_TOP_TO_BOTTOM; + else if (y == -1 && x == 0) + return READ_BOTTOM_TO_TOP; + + + WARN_ONCE(true, "The inverse of the rotation gives an incorrect direction."); + return READ_LEFT_TO_RIGHT; +} + /** * blend - blend the pixels from all planes and compute crc * @wb: The writeback frame buffer metadata diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h index 17081effe99a..5d0e87fe50c0 100644 --- a/drivers/gpu/drm/vkms/vkms_drv.h +++ b/drivers/gpu/drm/vkms/vkms_drv.h @@ -69,6 +69,17 @@ struct vkms_writeback_job { pixel_write_t pixel_write; }; +/** + * enum pixel_read_direction - Enum used internaly by VKMS to represent a reading direction in a + * plane. + */ +enum pixel_read_direction { + READ_BOTTOM_TO_TOP, + READ_TOP_TO_BOTTOM, + READ_RIGHT_TO_LEFT, + READ_LEFT_TO_RIGHT +}; + /** * typedef pixel_read_t - These functions are used to read a pixel in the source frame, * convert it to `struct pixel_argb_u16` and write it to @out_pixel. diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c index 9a1400ad4db6..e4cc8948e4d5 100644 --- a/drivers/gpu/drm/vkms/vkms_formats.c +++ b/drivers/gpu/drm/vkms/vkms_formats.c @@ -75,6 +75,36 @@ static void packed_pixels_addr(const struct vkms_frame_info *frame_info, *addr = (u8 *)frame_info->map[0].vaddr + offset; } +/** + * get_block_step_bytes() - Common helper to compute the correct step value between each pixel block + * to read in a certain direction. + * + * @fb: Framebuffer to iter on + * @direction: Direction of the reading + * @plane_index: Plane to get the step from + * + * As the returned count is the number of bytes between two consecutive blocks in a direction, + * the caller may have to read multiple pixels before using the next one (for example, to read from + * left to right in a DRM_FORMAT_R1 plane, each block contains 8 pixels, so the step must be used + * only every 8 pixels). + */ +static int get_block_step_bytes(struct drm_framebuffer *fb, enum pixel_read_direction direction, + int plane_index) +{ + switch (direction) { + case READ_LEFT_TO_RIGHT: + return fb->format->char_per_block[plane_index]; + case READ_RIGHT_TO_LEFT: + return -fb->format->char_per_block[plane_index]; + case READ_TOP_TO_BOTTOM: + return (int)fb->pitches[plane_index]; + case READ_BOTTOM_TO_TOP: + return -(int)fb->pitches[plane_index]; + } + + return 0; +} + /** * packed_pixels_addr_1x1() - Get the pointer to the block containing the pixel at the given * coordinates -- 2.43.2