Add support to convert from XR24 to reversed monochrome for drivers that control monochromatic display panels, that only have 1 bit per pixel.
The function does a line-by-line conversion doing an intermediate step first from XR24 to 8-bit grayscale and then to reversed monochrome.
The drm_fb_gray8_to_mono_reversed_line() helper was based on code from drivers/gpu/drm/tiny/repaper.c driver.
Signed-off-by: Javier Martinez Canillas javierm@redhat.com Reviewed-by: Thomas Zimmermann tzimmermann@suse.de Reviewed-by: Andy Shevchenko andriy.shevchenko@linux.intel.com ---
Changes in v6: - Add Andy Shevchenko's Reviewed-by to patch #2.
Changes in v5: - Use drm_WARN_ON* macros instead of deprecated ones (Thomas Zimmermann)
Changes in v4: - Rename end_offset to end_len (Thomas Zimmermann) - Warn once if dst_pitch is not a multiple of 8 (Thomas Zimmermann) - Drop drm_fb_gray8_to_mono_reversed() that's not used (Thomas Zimmermann) - Allocate single buffer for both copy cma memory and gray8 (Thomas Zimmermann) - Add Thomas Zimmermann Reviewed-by tag to patch adding XR24 -> mono helper.
Changes in v3: - Also add a drm_fb_xrgb8888_to_mono_reversed() helper (Thomas Zimmermann) - Split lines copy to drm_fb_gray8_to_mono_reversed_line() (Thomas Zimmermann) - Handle case where the source buffer is not aligned to 8 (Thomas Zimmermann)
drivers/gpu/drm/drm_format_helper.c | 110 ++++++++++++++++++++++++++++ include/drm/drm_format_helper.h | 4 + 2 files changed, 114 insertions(+)
diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c index b981712623d3..bc0f49773868 100644 --- a/drivers/gpu/drm/drm_format_helper.c +++ b/drivers/gpu/drm/drm_format_helper.c @@ -12,9 +12,11 @@ #include <linux/slab.h> #include <linux/io.h>
+#include <drm/drm_device.h> #include <drm/drm_format_helper.h> #include <drm/drm_framebuffer.h> #include <drm/drm_fourcc.h> +#include <drm/drm_print.h> #include <drm/drm_rect.h>
static unsigned int clip_offset(const struct drm_rect *clip, unsigned int pitch, unsigned int cpp) @@ -591,3 +593,111 @@ 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, 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; + + byte >>= 1; + if (src[x] >> 7) + byte |= BIT(7); + } + *dst++ = byte; + } +} + +/** + * 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 *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 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; + + if (drm_WARN_ON(dev, fb->format->format != DRM_FORMAT_XRGB8888)) + return; + + /* + * The reversed mono destination buffer contains 1 bit per pixel + * and destination scanlines have to be in multiple of 8 pixels. + */ + 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. + * + * Also, format conversion from XR24 to reversed monochrome + * 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 = kmalloc(len_src32 + linepixels, GFP_KERNEL); + if (!src32) + return; + + 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 reversed 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_reversed_line(mono, gray8, dst_pitch, + start_offset, end_len); + vaddr += fb->pitches[0]; + mono += dst_pitch; + } + + kfree(src32); +} +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..0b0937c0b2f6 100644 --- a/include/drm/drm_format_helper.h +++ b/include/drm/drm_format_helper.h @@ -43,4 +43,8 @@ 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_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 */