From: Rodrigo Siqueira <[email protected]>
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.
Signed-off-by: Rodrigo Siqueira <[email protected]>
---
drivers/gpu/drm/vkms/vkms_composer.c | 31 +++++++++++++++++-----------
1 file changed, 19 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index 258e659ecfba..686d25e7b01d 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -9,33 +9,40 @@
#include "vkms_drv.h"
+static u32 get_pixel_from_buffer(int x, int y, const u8 *buffer,
+ const struct vkms_composer *composer)
+{
+ int src_offset = composer->offset + (y * composer->pitch)
+ + (x * composer->cpp);
+
+ return *(u32 *)&buffer[src_offset];
+}
+
/**
* 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;
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;
+ u32 crc = 0, pixel = 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);
+ for (y = y_src; y < y_src + h_src; ++y) {
+ for (x = x_src; x < x_src + w_src; ++x) {
/* XRGB format ignores Alpha channel */
- memset(vaddr_out + src_offset + 24, 0, 8);
- crc = crc32_le(crc, vaddr_out + src_offset,
- sizeof(u32));
+ pixel = get_pixel_from_buffer(x, y, vaddr, composer);
+ bitmap_clear((void *)&pixel, 0, 8);
+ crc = crc32_le(crc, (void *)&pixel, sizeof(u32));
}
}
--
2.26.2
Hi Rodrigo,
On Mon, 11 May 2020 at 12:55, Rodrigo Siqueira <[email protected]> wrote:
>
> From: Rodrigo Siqueira <[email protected]>
>
> 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.
>
> Signed-off-by: Rodrigo Siqueira <[email protected]>
> ---
> drivers/gpu/drm/vkms/vkms_composer.c | 31 +++++++++++++++++-----------
> 1 file changed, 19 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> index 258e659ecfba..686d25e7b01d 100644
> --- a/drivers/gpu/drm/vkms/vkms_composer.c
> +++ b/drivers/gpu/drm/vkms/vkms_composer.c
> @@ -9,33 +9,40 @@
>
> #include "vkms_drv.h"
>
> +static u32 get_pixel_from_buffer(int x, int y, const u8 *buffer,
> + const struct vkms_composer *composer)
> +{
> + int src_offset = composer->offset + (y * composer->pitch)
> + + (x * composer->cpp);
> +
> + return *(u32 *)&buffer[src_offset];
> +}
> +
> /**
> * 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;
> 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;
> + u32 crc = 0, pixel = 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);
> + for (y = y_src; y < y_src + h_src; ++y) {
> + for (x = x_src; x < x_src + w_src; ++x) {
> /* XRGB format ignores Alpha channel */
> - memset(vaddr_out + src_offset + 24, 0, 8);
> - crc = crc32_le(crc, vaddr_out + src_offset,
> - sizeof(u32));
> + pixel = get_pixel_from_buffer(x, y, vaddr, composer);
> + bitmap_clear((void *)&pixel, 0, 8);
> + crc = crc32_le(crc, (void *)&pixel, sizeof(u32));
> }
> }
>
IMHO using something like the following makes the code far simpler and clearer.
offset = composer->offset + (y_src * composer->pitch) + (x_src * composer->cpp);
for (i = 0; i < h_src; i++, offset += composer->pitch) {
for (j = 0; j < w_src; j++, offset += composer->cpp) {
pixel = get_pixel_from_buffer(vaddr, offset);
crc = crc32_le(crc, &pixel, sizeof(u32); // cast should not be needed
}
}
With the bitmap_clear() and related comment moved into get_pixel_from_buffer().
-Emil
On Tue, 12 May 2020 at 12:34, Emil Velikov <[email protected]> wrote:
>
> Hi Rodrigo,
>
> On Mon, 11 May 2020 at 12:55, Rodrigo Siqueira <[email protected]> wrote:
> >
> > From: Rodrigo Siqueira <[email protected]>
> >
> > 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.
> >
> > Signed-off-by: Rodrigo Siqueira <[email protected]>
> > ---
> > drivers/gpu/drm/vkms/vkms_composer.c | 31 +++++++++++++++++-----------
> > 1 file changed, 19 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> > index 258e659ecfba..686d25e7b01d 100644
> > --- a/drivers/gpu/drm/vkms/vkms_composer.c
> > +++ b/drivers/gpu/drm/vkms/vkms_composer.c
> > @@ -9,33 +9,40 @@
> >
> > #include "vkms_drv.h"
> >
> > +static u32 get_pixel_from_buffer(int x, int y, const u8 *buffer,
> > + const struct vkms_composer *composer)
> > +{
> > + int src_offset = composer->offset + (y * composer->pitch)
> > + + (x * composer->cpp);
> > +
> > + return *(u32 *)&buffer[src_offset];
> > +}
> > +
> > /**
> > * 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;
> > 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;
> > + u32 crc = 0, pixel = 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);
> > + for (y = y_src; y < y_src + h_src; ++y) {
> > + for (x = x_src; x < x_src + w_src; ++x) {
> > /* XRGB format ignores Alpha channel */
> > - memset(vaddr_out + src_offset + 24, 0, 8);
> > - crc = crc32_le(crc, vaddr_out + src_offset,
> > - sizeof(u32));
> > + pixel = get_pixel_from_buffer(x, y, vaddr, composer);
> > + bitmap_clear((void *)&pixel, 0, 8);
> > + crc = crc32_le(crc, (void *)&pixel, sizeof(u32));
> > }
> > }
> >
> IMHO using something like the following makes the code far simpler and clearer.
>
> offset = composer->offset + (y_src * composer->pitch) + (x_src * composer->cpp);
>
> for (i = 0; i < h_src; i++, offset += composer->pitch) {
> for (j = 0; j < w_src; j++, offset += composer->cpp) {
> pixel = get_pixel_from_buffer(vaddr, offset);
> crc = crc32_le(crc, &pixel, sizeof(u32); // cast should not be needed
> }
> }
>
> With the bitmap_clear() and related comment moved into get_pixel_from_buffer().
>
If you fold the bitmap_clear() in get_pixel_from_buffer(), and drop
the cast (unless I'm missing something and it's really needed) for
crc32_le() this patch is:
Reviewed-by: Emil Velikov <[email protected]>
I would suggest (but it's not a requirement) that you simplify the
loop/offset calculation as separate patch in v5.
-Emil