From: Geert Uytterhoeven geert@linux-m68k.org
[ Upstream commit 7392f2459eefcdab1d998af002d2b8b16fe4a2fd ]
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: bcf8b616deb87941 ("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... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/drm_format_helper.c | 55 ++++++++++------------------- 1 file changed, 18 insertions(+), 37 deletions(-)
diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c index 5d9d0c695845..e085f855a199 100644 --- a/drivers/gpu/drm/drm_format_helper.c +++ b/drivers/gpu/drm/drm_format_helper.c @@ -594,27 +594,16 @@ int drm_fb_blit_toio(void __iomem *dst, unsigned int dst_pitch, uint32_t dst_for } EXPORT_SYMBOL(drm_fb_blit_toio);
-static void drm_fb_gray8_to_mono_line(u8 *dst, const u8 *src, unsigned int pixels, - unsigned int start_offset, unsigned int end_len) -{ - unsigned int xb, i; - - for (xb = 0; xb < pixels; xb++) { - unsigned int start = 0, end = 8; - u8 byte = 0x00; - - if (xb == 0 && start_offset) - start = start_offset;
- if (xb == pixels - 1 && end_len) - end = end_len; - - for (i = start; i < end; i++) { - unsigned int x = xb * 8 + i; +static void drm_fb_gray8_to_mono_line(u8 *dst, const u8 *src, unsigned int pixels) +{ + while (pixels) { + unsigned int i, bits = min(pixels, 8U); + u8 byte = 0;
- byte >>= 1; - if (src[x] >> 7) - byte |= BIT(7); + for (i = 0; i < bits; i++, pixels--) { + if (*src++ >= 128) + byte |= BIT(i); } *dst++ = byte; } @@ -634,16 +623,22 @@ static void drm_fb_gray8_to_mono_line(u8 *dst, const u8 *src, unsigned int pixel * * This function uses drm_fb_xrgb8888_to_gray8() to convert to grayscale and * then the result is converted from grayscale to monochrome. + * + * The first pixel (upper left corner of the clip rectangle) will be converted + * and copied to the first bit (LSB) in the first byte of the monochrome + * destination buffer. + * If the caller requires that the first pixel in a byte must be located at an + * x-coordinate that is a multiple of 8, then the caller must take care itself + * of supplying a suitable clip rectangle. */ void drm_fb_xrgb8888_to_mono(void *dst, unsigned int dst_pitch, const void *vaddr, const struct drm_framebuffer *fb, const struct drm_rect *clip) { unsigned int linepixels = drm_rect_width(clip); - unsigned int lines = clip->y2 - clip->y1; + unsigned int lines = drm_rect_height(clip); unsigned int cpp = fb->format->cpp[0]; unsigned int len_src32 = linepixels * cpp; struct drm_device *dev = fb->dev; - unsigned int start_offset, end_len; unsigned int y; u8 *mono = dst, *gray8; u32 *src32; @@ -652,14 +647,11 @@ void drm_fb_xrgb8888_to_mono(void *dst, unsigned int dst_pitch, const void *vadd return;
/* - * The mono destination buffer contains 1 bit per pixel and - * destination scanlines have to be in multiple of 8 pixels. + * The mono destination buffer contains 1 bit per pixel */ if (!dst_pitch) dst_pitch = DIV_ROUND_UP(linepixels, 8);
- drm_WARN_ONCE(dev, dst_pitch % 8 != 0, "dst_pitch is not a multiple of 8\n"); - /* * The cma memory is write-combined so reads are uncached. * Speed up by fetching one line at a time. @@ -677,22 +669,11 @@ void drm_fb_xrgb8888_to_mono(void *dst, unsigned int dst_pitch, const void *vadd
gray8 = (u8 *)src32 + len_src32;
- /* - * For damage handling, it is possible that only parts of the source - * buffer is copied and this could lead to start and end pixels that - * are not aligned to multiple of 8. - * - * Calculate if the start and end pixels are not aligned and set the - * offsets for the mono line conversion function to adjust. - */ - start_offset = clip->x1 % 8; - end_len = clip->x2 % 8; - vaddr += clip_offset(clip, fb->pitches[0], cpp); for (y = 0; y < lines; y++) { src32 = memcpy(src32, vaddr, len_src32); drm_fb_xrgb8888_to_gray8_line(gray8, src32, linepixels); - drm_fb_gray8_to_mono_line(mono, gray8, dst_pitch, start_offset, end_len); + drm_fb_gray8_to_mono_line(mono, gray8, linepixels); vaddr += fb->pitches[0]; mono += dst_pitch; }