Re: [PATCH v5 1/6] drm/format-helper: Add drm_fb_xrgb8888_to_gray8_line()

Andy Shevchenko
2022-02-11T15:59:49Z

On Fri, Feb 11, 2022 at 03:33:53PM +0100, Javier Martinez Canillas wrote:
> Pull the per-line conversion logic into a separate helper function.
>
> This will allow to do line-by-line conversion in other helpers that
> convert to a gray8 format.

for-loop vs. while-loop is not critical, so
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>
> Changes in v5:
> - Add Thomas Zimmermann's Reviewed-by to patch #1.
>
> Changes in v3:
> - Add a drm_fb_xrgb8888_to_gray8_line() helper function (Thomas Zimmermann)
>
> drivers/gpu/drm/drm_format_helper.c | 31 ++++++++++++++++++-----------
> 1 file changed, 19 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> index 0f28dd2bdd72..b981712623d3 100644
> --- a/drivers/gpu/drm/drm_format_helper.c
> +++ b/drivers/gpu/drm/drm_format_helper.c
> @@ -464,6 +464,21 @@ void drm_fb_xrgb8888_to_xrgb2101010_toio(void __iomem *dst,
> }
> EXPORT_SYMBOL(drm_fb_xrgb8888_to_xrgb2101010_toio);
>
> +static void drm_fb_xrgb8888_to_gray8_line(u8 *dst, const u32 *src, unsigned int pixels)
> +{
> + unsigned int x;
> +
> + for (x = 0; x < pixels; x++) {
> + u8 r = (*src & 0x00ff0000) >> 16;
> + u8 g = (*src & 0x0000ff00) >> 8;
> + u8 b = *src & 0x000000ff;
> +
> + /* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
> + *dst++ = (3 * r + 6 * g + b) / 10;
> + src++;
> + }
> +}
> +
> /**
> * drm_fb_xrgb8888_to_gray8 - Convert XRGB8888 to grayscale
> * @dst: 8-bit grayscale destination buffer
> @@ -484,8 +499,9 @@ EXPORT_SYMBOL(drm_fb_xrgb8888_to_xrgb2101010_toio);
> void drm_fb_xrgb8888_to_gray8(void *dst, unsigned int dst_pitch, const void *vaddr,
> const struct drm_framebuffer *fb, const struct drm_rect *clip)
> {
> - unsigned int len = (clip->x2 - clip->x1) * sizeof(u32);
> - unsigned int x, y;
> + unsigned int linepixels = clip->x2 - clip->x1;
> + unsigned int len = linepixels * sizeof(u32);
> + unsigned int y;
> void *buf;
> u8 *dst8;
> u32 *src32;
> @@ -508,16 +524,7 @@ void drm_fb_xrgb8888_to_gray8(void *dst, unsigned int dst_pitch, const void *vad
> for (y = clip->y1; y < clip->y2; y++) {
> dst8 = dst;
> src32 = memcpy(buf, vaddr, len);
> - for (x = clip->x1; x < clip->x2; x++) {
> - u8 r = (*src32 & 0x00ff0000) >> 16;
> - u8 g = (*src32 & 0x0000ff00) >> 8;
> - u8 b = *src32 & 0x000000ff;
> -
> - /* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
> - *dst8++ = (3 * r + 6 * g + b) / 10;
> - src32++;
> - }
> -
> + drm_fb_xrgb8888_to_gray8_line(dst8, src32, linepixels);
> vaddr += fb->pitches[0];
> dst += dst_pitch;
> }
> --
> 2.34.1
>

--
With Best Regards,
Andy Shevchenko