From 8bde81ec684238587decd5ab6b1bf18041814937 Mon Sep 17 00:00:00 2001 From: Marcus Folkesson Date: Mon, 21 Jul 2025 12:43:35 +0200 Subject: [PATCH 4930/5403] drm/format-helper: introduce drm_fb_xrgb8888_to_gray2() Convert XRGB8888 to 2bit grayscale. It uses drm_fb_xrgb8888_to_gray8() to convert the pixels to gray8 as an intermediate step before converting to gray2. Signed-off-by: Marcus Folkesson Reviewed-by: Javier Martinez Canillas Acked-by: Thomas Zimmermann Link: https://lore.kernel.org/r/20250721-st7571-format-v2-5-159f4134098c@gmail.com Signed-off-by: Javier Martinez Canillas --- drivers/gpu/drm/drm_format_helper.c | 108 ++++++++++++++++++++++++++++ include/drm/drm_format_helper.h | 4 ++ 2 files changed, 112 insertions(+) diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c index 37d5e0a7eb46..006836554cc2 100644 --- a/drivers/gpu/drm/drm_format_helper.c +++ b/drivers/gpu/drm/drm_format_helper.c @@ -1256,6 +1256,25 @@ int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d } EXPORT_SYMBOL(drm_fb_blit); +static void drm_fb_gray8_to_gray2_line(void *dbuf, const void *sbuf, unsigned int pixels) +{ + u8 *dbuf8 = dbuf; + const u8 *sbuf8 = sbuf; + u8 px; + + while (pixels) { + unsigned int i, bits = min(pixels, 4U); + u8 byte = 0; + + for (i = 0; i < bits; i++, pixels--) { + byte >>= 2; + px = (*sbuf8++ * 3 + 127) / 255; + byte |= (px &= 0x03) << 6; + } + *dbuf8++ = byte; + } +} + static void drm_fb_gray8_to_mono_line(void *dbuf, const void *sbuf, unsigned int pixels) { u8 *dbuf8 = dbuf; @@ -1362,3 +1381,92 @@ void drm_fb_xrgb8888_to_mono(struct iosys_map *dst, const unsigned int *dst_pitc } } EXPORT_SYMBOL(drm_fb_xrgb8888_to_mono); + +/** + * drm_fb_xrgb8888_to_gray2 - Convert XRGB8888 to gray2 + * @dst: Array of gray2 destination buffer + * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines + * within @dst; can be NULL if scanlines are stored next to each other. + * @src: Array of XRGB8888 source buffers + * @fb: DRM framebuffer + * @clip: Clip rectangle area to copy + * @state: Transform and conversion state + * + * This function copies parts of a framebuffer to display memory and converts the + * color format during the process. Destination and framebuffer formats must match. The + * parameters @dst, @dst_pitch and @src refer to arrays. Each array must have at + * least as many entries as there are planes in @fb's format. Each entry stores the + * value for the format's respective color plane at the same index. + * + * This function does not apply clipping on @dst (i.e. the destination is at the + * top-left corner). The first pixel (upper left corner of the clip rectangle) will + * be converted and copied to the two first bits (LSB) in the first byte of the gray2 + * 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. + * + * DRM doesn't have native gray2 support. Drivers can use this function for + * gray2 devices that don't support XRGB8888 natively. Such drivers can + * announce the commonly supported XR24 format to userspace and use this function + * to convert to the native format. + * + */ +void drm_fb_xrgb8888_to_gray2(struct iosys_map *dst, const unsigned int *dst_pitch, + const struct iosys_map *src, const struct drm_framebuffer *fb, + const struct drm_rect *clip, struct drm_format_conv_state *state) +{ + static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = { + 0, 0, 0, 0 + }; + unsigned int linepixels = drm_rect_width(clip); + 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; + void *vaddr = src[0].vaddr; + unsigned int dst_pitch_0; + unsigned int y; + u8 *gray2 = dst[0].vaddr, *gray8; + u32 *src32; + + if (drm_WARN_ON(dev, fb->format->format != DRM_FORMAT_XRGB8888)) + return; + + if (!dst_pitch) + dst_pitch = default_dst_pitch; + dst_pitch_0 = dst_pitch[0]; + + /* + * The gray2 destination buffer contains 2 bit per pixel + */ + if (!dst_pitch_0) + dst_pitch_0 = DIV_ROUND_UP(linepixels, 4); + + /* + * The dma memory is write-combined so reads are uncached. + * Speed up by fetching one line at a time. + * + * Also, format conversion from XR24 to gray2 are done + * line-by-line but are converted to 8-bit grayscale as an + * intermediate step. + * + * Allocate a buffer to be used for both copying from the cma + * memory and to store the intermediate grayscale line pixels. + */ + src32 = drm_format_conv_state_reserve(state, len_src32 + linepixels, GFP_KERNEL); + if (!src32) + return; + + gray8 = (u8 *)src32 + len_src32; + + 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_gray2_line(gray2, gray8, linepixels); + vaddr += fb->pitches[0]; + gray2 += dst_pitch_0; + } +} +EXPORT_SYMBOL(drm_fb_xrgb8888_to_gray2); + diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h index 562bc383ece4..32d57d6c5327 100644 --- a/include/drm/drm_format_helper.h +++ b/include/drm/drm_format_helper.h @@ -136,4 +136,8 @@ void drm_fb_xrgb8888_to_mono(struct iosys_map *dst, const unsigned int *dst_pitc const struct iosys_map *src, const struct drm_framebuffer *fb, const struct drm_rect *clip, struct drm_format_conv_state *state); +void drm_fb_xrgb8888_to_gray2(struct iosys_map *dst, const unsigned int *dst_pitch, + const struct iosys_map *src, const struct drm_framebuffer *fb, + const struct drm_rect *clip, struct drm_format_conv_state *state); + #endif /* __LINUX_DRM_FORMAT_HELPER_H */ -- 2.54.0