drm/format-helper: Fix XRGB888 to monochrome conversion
The conversion functions drm_fb_xrgb8888_to_mono() and
drm_fb_gray8_to_mono_line() do not behave correctly when the
horizontal boundaries of the clip rectangle are not multiples of 8:
a. When x1 % 8 != 0, the calculated pitch is not correct,
b. When x2 % 8 != 0, the pixel data for the last byte is wrong.
Simplify the code and fix (a) by:
1. Removing start_offset, and always storing the first pixel in the
first bit of the monochrome destination buffer.
Drivers that require the first pixel in a byte to be located at an
x-coordinate that is a multiple of 8 can always align the clip
rectangle before calling drm_fb_xrgb8888_to_mono().
Note that:
- The ssd130x driver does not need the alignment, as the
monochrome buffer is a temporary format,
- The repaper driver always updates the full screen, so the clip
rectangle is always aligned.
2. Passing the number of pixels to drm_fb_gray8_to_mono_line(),
instead of the number of bytes, and the number of pixels in the
last byte.
Fix (b) by explicitly setting the target bit, instead of always setting
bit 7 and shifting the value in each loop iteration.
Remove the bogus pitch check, which operates on bytes instead of pixels,
and triggers when e.g. flashing the cursor on a text console with a font
that is 8 pixels wide.
Drop the confusing comment about scanlines, as a pitch in bytes always
contains a multiple of 8 pixels.
While at it, use the drm_rect_height() helper instead of open-coding the
same operation.
Update the comments accordingly.
Fixes: bcf8b616de
("drm/format-helper: Add drm_fb_xrgb8888_to_mono_reversed()")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220317081830.1211400-3-geert@linux-m68k.org
This commit is contained in:
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@ -594,27 +594,16 @@ int drm_fb_blit_toio(void __iomem *dst, unsigned int dst_pitch, uint32_t dst_for
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}
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EXPORT_SYMBOL(drm_fb_blit_toio);
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static void drm_fb_gray8_to_mono_line(u8 *dst, const u8 *src, unsigned int pixels,
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unsigned int start_offset, unsigned int end_len)
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static void drm_fb_gray8_to_mono_line(u8 *dst, const u8 *src, unsigned int pixels)
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{
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unsigned int xb, i;
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while (pixels) {
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unsigned int i, bits = min(pixels, 8U);
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u8 byte = 0;
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for (xb = 0; xb < pixels; xb++) {
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unsigned int start = 0, end = 8;
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u8 byte = 0x00;
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if (xb == 0 && start_offset)
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start = start_offset;
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if (xb == pixels - 1 && end_len)
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end = end_len;
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for (i = start; i < end; i++) {
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unsigned int x = xb * 8 + i;
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byte >>= 1;
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if (src[x] >> 7)
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byte |= BIT(7);
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for (i = 0; i < bits; i++, pixels--) {
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if (*src++ >= 128)
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byte |= BIT(i);
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}
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*dst++ = byte;
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}
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@ -634,16 +623,22 @@ static void drm_fb_gray8_to_mono_line(u8 *dst, const u8 *src, unsigned int pixel
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*
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* This function uses drm_fb_xrgb8888_to_gray8() to convert to grayscale and
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* then the result is converted from grayscale to monochrome.
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*
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* The first pixel (upper left corner of the clip rectangle) will be converted
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* and copied to the first bit (LSB) in the first byte of the monochrome
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* destination buffer.
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* If the caller requires that the first pixel in a byte must be located at an
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* x-coordinate that is a multiple of 8, then the caller must take care itself
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* of supplying a suitable clip rectangle.
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*/
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void drm_fb_xrgb8888_to_mono(void *dst, unsigned int dst_pitch, const void *vaddr,
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const struct drm_framebuffer *fb, const struct drm_rect *clip)
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{
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unsigned int linepixels = drm_rect_width(clip);
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unsigned int lines = clip->y2 - clip->y1;
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unsigned int lines = drm_rect_height(clip);
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unsigned int cpp = fb->format->cpp[0];
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unsigned int len_src32 = linepixels * cpp;
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struct drm_device *dev = fb->dev;
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unsigned int start_offset, end_len;
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unsigned int y;
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u8 *mono = dst, *gray8;
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u32 *src32;
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@ -652,14 +647,11 @@ void drm_fb_xrgb8888_to_mono(void *dst, unsigned int dst_pitch, const void *vadd
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return;
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/*
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* The mono destination buffer contains 1 bit per pixel and
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* destination scanlines have to be in multiple of 8 pixels.
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* The mono destination buffer contains 1 bit per pixel
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*/
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if (!dst_pitch)
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dst_pitch = DIV_ROUND_UP(linepixels, 8);
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drm_WARN_ONCE(dev, dst_pitch % 8 != 0, "dst_pitch is not a multiple of 8\n");
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/*
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* The cma memory is write-combined so reads are uncached.
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* Speed up by fetching one line at a time.
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@ -677,22 +669,11 @@ void drm_fb_xrgb8888_to_mono(void *dst, unsigned int dst_pitch, const void *vadd
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gray8 = (u8 *)src32 + len_src32;
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/*
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* For damage handling, it is possible that only parts of the source
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* buffer is copied and this could lead to start and end pixels that
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* are not aligned to multiple of 8.
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*
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* Calculate if the start and end pixels are not aligned and set the
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* offsets for the mono line conversion function to adjust.
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*/
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start_offset = clip->x1 % 8;
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end_len = clip->x2 % 8;
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vaddr += clip_offset(clip, fb->pitches[0], cpp);
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for (y = 0; y < lines; y++) {
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src32 = memcpy(src32, vaddr, len_src32);
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drm_fb_xrgb8888_to_gray8_line(gray8, src32, linepixels);
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drm_fb_gray8_to_mono_line(mono, gray8, dst_pitch, start_offset, end_len);
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drm_fb_gray8_to_mono_line(mono, gray8, linepixels);
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vaddr += fb->pitches[0];
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mono += dst_pitch;
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}
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