Hi Am 31.01.22 um 21:12 schrieb Javier Martinez Canillas:
Add support to convert 8-bit grayscale to reversed monochrome for drivers that control monochromatic displays, that only have 1 bit per pixel depth.This helper function was based on repaper_gray8_to_mono_reversed() from the drivers/gpu/drm/tiny/repaper.c driver.
You could convert repaper to the new helper.
Signed-off-by: Javier Martinez Canillas <javi...@redhat.com>
---
drivers/gpu/drm/drm_format_helper.c | 35 +++++++++++++++++++++++++++++
include/drm/drm_format_helper.h | 2 ++
2 files changed, 37 insertions(+)
diff --git a/drivers/gpu/drm/drm_format_helper.c
b/drivers/gpu/drm/drm_format_helper.c
index 0f28dd2bdd72..bf477c136082 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -584,3 +584,38 @@ int drm_fb_blit_toio(void __iomem *dst, unsigned int
dst_pitch, uint32_t dst_for
return -EINVAL;
}
EXPORT_SYMBOL(drm_fb_blit_toio);
+
+/**
+ * drm_fb_gray8_to_mono_reversed - Convert grayscale to reversed monochrome
+ * @dst: reversed monochrome destination buffer
+ * @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, void *src, const struct drm_rect
*clip)
IMHO it would be better to have a function that converts xrgb8888 to mono and let it handle the intermediate step of gray8.
+{
+ size_t width = drm_rect_width(clip);
+ size_t height = drm_rect_width(clip);
+
+ u8 *mono = dst, *gray8 = src;
+ unsigned int y, xb, i;
+
+ for (y = 0; y < height; y++)
+ for (xb = 0; xb < width / 8; xb++) {
The inner loop should probably go into a separate helper function. See the drm_fb_*_line() helpers in this file
At some point, we's want to have a single blit helper that takes source and destination formats/buffers. It would then pick the correct per-line helper for the conversion. So yeah, we'd want something composable.
Best regards Thomas
+ u8 byte = 0x00; + + for (i = 0; i < 8; i++) { + int x = xb * 8 + i; + + byte >>= 1; + if (gray8[y * width + x] >> 7) + byte |= BIT(7); + } + *mono++ = byte; + } +} +EXPORT_SYMBOL(drm_fb_gray8_to_mono_reversed); diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h index b30ed5de0a33..cd4c8b7c78de 100644 --- a/include/drm/drm_format_helper.h +++ b/include/drm/drm_format_helper.h @@ -43,4 +43,6 @@ 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, void *vaddr, const struct drm_rect *clip);+ #endif /* __LINUX_DRM_FORMAT_HELPER_H */
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
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