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@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++) {
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 */
-- 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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