Am 04.02.22 um 16:52 schrieb Thomas Zimmermann: [...]
+/**
- drm_fb_xrgb8888_to_mono_reversed - Convert XRGB8888 to reversed
monochrome
- @dst: reversed monochrome destination buffer
- @dst_pitch: Number of bytes between two consecutive scanlines
within dst
- @src: XRGB8888 source buffer
- @fb: DRM framebuffer
- @clip: Clip rectangle area to copy
- DRM doesn't have native monochrome support.
- Such drivers can announce the commonly supported XR24 format to
userspace
- and use this function to convert to the native format.
- This function uses drm_fb_xrgb8888_to_gray8() to convert to
grayscale and
- then the result is converted from grayscale to reversed monohrome.
- */
+void drm_fb_xrgb8888_to_mono_reversed(void *dst, unsigned int dst_pitch, const void *src, + const struct drm_framebuffer *fb, + const struct drm_rect *clip) +{ + if (WARN_ON(fb->format->format != DRM_FORMAT_XRGB8888)) + return;
+ if (!dst_pitch) + dst_pitch = drm_rect_width(clip);
+ drm_fb_xrgb8888_to_gray8(dst, dst_pitch, src, fb, clip); + drm_fb_gray8_to_mono_reversed(dst, dst_pitch, dst, fb, clip);
Converting from dst into dst can give incorrect results. At some point we probably want to add restrict qualifiers to these pointers, to help the compiler with optimizing.
A better approach here is to pull the per-line conversion from drm_fb_xrgb8888_to_gray8() into a separate helper and implement a line-by-line conversion here. something like this:
drm_fb_xrgb8888_to_mono_reversed() { char *tmp = kmalloc(size of a single line of gray8)
for (heigth) { drm_fb_xrgb8888_to_gray8_line(tmp, ..., src, ...); drm_fb_gray8_to_mono_reversed(dst, ..., tmp, ...);
Here, I meant 'drm_fb_gray8_to_mono_reversed_line()'
src += fb->pitches[0] dst += dst_pitch; }
kfree(tmp); }
To elaborate, this is an example of what I meant by composable. In the future, we can generalize this function and hand-in 2 function pointers the do the conversion with tmp as intermediate buffer. That would work for any combination of formats that have a common intermediate format.
Best regards Thomas
+} +EXPORT_SYMBOL(drm_fb_xrgb8888_to_mono_reversed); diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h index b30ed5de0a33..85e551a5cbe6 100644 --- a/include/drm/drm_format_helper.h +++ b/include/drm/drm_format_helper.h @@ -43,4 +43,11 @@ int drm_fb_blit_toio(void __iomem *dst, unsigned int dst_pitch, uint32_t dst_for const void *vmap, const struct drm_framebuffer *fb, const struct drm_rect *rect); +void drm_fb_gray8_to_mono_reversed(void *dst, unsigned int dst_pitch, const void *src, + const struct drm_rect *clip);
+void drm_fb_xrgb8888_to_mono_reversed(void *dst, unsigned int dst_pitch, const void *src, + const struct drm_framebuffer *fb, + const struct drm_rect *clip);
#endif /* __LINUX_DRM_FORMAT_HELPER_H */