[PATCH 2/4] drm/format-helper: Add drm_fb_gray8_to_mono_reversed()
From: Javier Martinez Canillas <javierm@redhat.com>
Date: 2022-01-31 20:12:58
Also in:
dri-devel, lkml
Subsystem:
drm drivers, drm drivers and misc gpu patches, the rest · Maintainers:
David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, Linus Torvalds
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. Signed-off-by: Javier Martinez Canillas <javierm@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) +{ + 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++) { + 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 */
--
2.34.1