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@xxxxxxxxxx>
---
(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++) {
+ 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)
+{
+
+ 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;
+
+ for (y = 0; y < height; y++) {
+ drm_fb_gray8_to_mono_reversed_line(mono, gray8, dst_pitch);
+ mono += (dst_pitch / 8);
+ gray8 += dst_pitch;
+ }
+}
+
+/**
+ * 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);
+}
+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 */
--
2.34.1
