Hi
Am 04.02.22 um 14:43 schrieb Javier Martinez Canillas:
Add support to convert XR24 and 8-bit grayscale to reversed monochrome for drivers that control monochromatic panels, that only have 1 bit per pixel.
The drm_fb_gray8_to_mono_reversed() helper was based on the function that does the same in the drivers/gpu/drm/tiny/repaper.c driver.
Signed-off-by: Javier Martinez Canillas javierm@redhat.com
(no changes since v1)
drivers/gpu/drm/drm_format_helper.c | 80 +++++++++++++++++++++++++++++ include/drm/drm_format_helper.h | 7 +++ 2 files changed, 87 insertions(+)
diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c index 0f28dd2bdd72..cdce4b7c25d9 100644 --- a/drivers/gpu/drm/drm_format_helper.c +++ b/drivers/gpu/drm/drm_format_helper.c @@ -584,3 +584,83 @@ int drm_fb_blit_toio(void __iomem *dst, unsigned int dst_pitch, uint32_t dst_for return -EINVAL; } EXPORT_SYMBOL(drm_fb_blit_toio);
+static void drm_fb_gray8_to_mono_reversed_line(u8 *dst, const u8 *src, size_t pixels) +{
- unsigned int xb, i;
- for (xb = 0; xb < pixels / 8; xb++) {
In practice, all mode widths are multiples of 8 because VGA mandated it. So it's ok-ish to assume this here. You should probably at least print a warning somewhere if (pixels % 8 != 0)
u8 byte = 0x00;for (i = 0; i < 8; i++) {int x = xb * 8 + i;byte >>= 1;if (src[x] >> 7)byte |= BIT(7);}*dst++ = byte;- }
+}
+/**
- drm_fb_gray8_to_mono_reversed - Convert grayscale to reversed monochrome
- @dst: reversed monochrome destination buffer
- @dst_pitch: Number of bytes between two consecutive scanlines within dst
- @src: 8-bit grayscale source buffer
- @clip: Clip rectangle area to copy
- DRM doesn't have native monochrome or grayscale support.
- Such drivers can announce the commonly supported XR24 format to userspace
- and use drm_fb_xrgb8888_to_gray8() to convert to grayscale and then this
- helper function to convert to the native format.
- */
+void drm_fb_gray8_to_mono_reversed(void *dst, unsigned int dst_pitch, const void *src,
const struct drm_rect *clip)
There's a bug here. You want to pass in a drm_framebuffer as fourth argument.
+{
- size_t height = drm_rect_height(clip);
- size_t width = drm_rect_width(clip);
- unsigned int y;
- const u8 *gray8 = src;
- u8 *mono = dst;
- if (!dst_pitch)
dst_pitch = width;
The dst_pitch is given in bytes. You have to device by 8. Here would be a good place to warn if (width % 8 != 0).
- for (y = 0; y < height; y++) {
drm_fb_gray8_to_mono_reversed_line(mono, gray8, dst_pitch);mono += (dst_pitch / 8);
The dst_pitch is already given in bytes.
gray8 += dst_pitch;
'gray8 += fb->pitches[0]' would be correct.
- }
+}
+/**
- 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, ...);
src += fb->pitches[0] dst += dst_pitch; }
kfree(tmp); }
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 */