The compute_crc() function is responsible for calculating the framebuffer CRC value; due to the XRGB format, this function has to ignore the alpha channel during the CRC computation. Therefore, compute_crc() set zero to the alpha channel directly in the input framebuffer, which is not a problem since this function receives a copy of the original buffer. However, if we want to use this function in a context without a buffer copy, it will change the initial value. This patch makes compute_crc() calculate the CRC value without modifying the input framebuffer.
Change in V4 (Emil): - Move bitmap_clear operation and comments to get_pixel function
Signed-off-by: Rodrigo Siqueira rodrigosiqueiramelo@gmail.com --- drivers/gpu/drm/vkms/vkms_composer.c | 38 ++++++++++++++++++---------- 1 file changed, 24 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c index 4d8bc04bb6ee..387b0690a64a 100644 --- a/drivers/gpu/drm/vkms/vkms_composer.c +++ b/drivers/gpu/drm/vkms/vkms_composer.c @@ -9,33 +9,43 @@
#include "vkms_drv.h"
+static u32 get_pixel_from_buffer(int x, int y, const u8 *buffer, + const struct vkms_composer *composer) +{ + u32 pixel; + int src_offset = composer->offset + (y * composer->pitch) + + (x * composer->cpp); + + pixel = *(u32 *)&buffer[src_offset]; + /* XRGB format ignores Alpha channel */ + bitmap_clear((void *)&pixel, 0, 8); + + return pixel; +} + /** * compute_crc - Compute CRC value on output frame * - * @vaddr_out: address to final framebuffer + * @vaddr: address to final framebuffer * @composer: framebuffer's metadata * * returns CRC value computed using crc32 on the visible portion of * the final framebuffer at vaddr_out */ -static uint32_t compute_crc(void *vaddr_out, struct vkms_composer *composer) +static uint32_t compute_crc(const u8 *vaddr, + const struct vkms_composer *composer) { - int i, j, src_offset; + int x, y; + u32 crc = 0, pixel = 0; int x_src = composer->src.x1 >> 16; int y_src = composer->src.y1 >> 16; int h_src = drm_rect_height(&composer->src) >> 16; int w_src = drm_rect_width(&composer->src) >> 16; - u32 crc = 0; - - for (i = y_src; i < y_src + h_src; ++i) { - for (j = x_src; j < x_src + w_src; ++j) { - src_offset = composer->offset - + (i * composer->pitch) - + (j * composer->cpp); - /* XRGB format ignores Alpha channel */ - bitmap_clear(vaddr_out + src_offset, 24, 8); - crc = crc32_le(crc, vaddr_out + src_offset, - sizeof(u32)); + + for (y = y_src; y < y_src + h_src; ++y) { + for (x = x_src; x < x_src + w_src; ++x) { + pixel = get_pixel_from_buffer(x, y, vaddr, composer); + crc = crc32_le(crc, (void *)&pixel, sizeof(u32)); } }