Den 31.08.2021 14.23, skrev Daniel Vetter: > On Mon, Aug 30, 2021 at 02:08:14PM +0200, Noralf Trønnes wrote: >> >> >> Den 17.08.2021 15.56, skrev Daniel Vetter: >>> On Tue, Aug 17, 2021 at 02:29:12PM +0200, Noralf Trønnes wrote: >>>> Add XRGB8888 emulation support for devices that can only do RGB332. >>>> >>>> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx> >>>> Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx> >>>> --- >>>> drivers/gpu/drm/drm_format_helper.c | 47 +++++++++++++++++++++++++++++ >>>> include/drm/drm_format_helper.h | 2 ++ >>>> 2 files changed, 49 insertions(+) >>>> >>>> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c >>>> index 5231104b1498..53b426da7467 100644 >>>> --- a/drivers/gpu/drm/drm_format_helper.c >>>> +++ b/drivers/gpu/drm/drm_format_helper.c >>>> @@ -135,6 +135,53 @@ void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb, >>>> } >>>> EXPORT_SYMBOL(drm_fb_swab); >>>> >>>> +static void drm_fb_xrgb8888_to_rgb332_line(u8 *dbuf, u32 *sbuf, unsigned int pixels) >>>> +{ >>>> + unsigned int x; >>>> + >>>> + for (x = 0; x < pixels; x++) >>>> + dbuf[x] = ((sbuf[x] & 0x00e00000) >> 16) | >>> >>> I think for 2/3 bits correct rounding would be useful, not just masking. >>> i.e. before you shift add 0x00100000 here, and similar below. >>> >> >> Math isn't my strongest side and my brain failed to turn this into code. > > Essentially add half of the lowest bit before you mask, so > > ((sbuf[x] + 0x10) & 0xe0 ) > But what if the value is 0xff, it overflows: ((0xff + 0x10) & 0xe0 ) == 0x00 Should it be OR? ((0xff | 0x10) & 0xe0 ) == 0xe0 Noralf. > I dropped the shift to make it clear what's going on. If you're mask is > 0xc0, then you simply add 0x20 before masking. > >>> Also I just realized we've totally ignored endianess on these, which is >>> not great, because strictly speaking all the drm_fourcc codes should be >>> little endian. But I'm also not sure that's worth fixing ... >>> >> >> Is it as simple as using le32_to_cpu()? > > I think so. > > Plus on any format that has u16 output we'd need a cpu_to_le16 wrapped > around the entire thing. > -Daniel > >> static void drm_fb_xrgb8888_to_rgb332_line(u8 *dbuf, __le32 *sbuf, >> unsigned int pixels) >> { >> unsigned int x; >> u32 pix; >> >> for (x = 0; x < pixels; x++) { >> pix = le32_to_cpu(sbuf[x]); >> dbuf[x] = ((pix & 0x00e00000) >> 16) | >> ((pix & 0x0000e000) >> 11) | >> ((pix & 0x000000c0) >> 6); >> } >> } >> >> Noralf. >> >>> Either way, lgtm: >>> >>> Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx> >>> >>>> + ((sbuf[x] & 0x0000e000) >> 11) | >>>> + ((sbuf[x] & 0x000000c0) >> 6); >>>> +} >>>> + >>>> +/** >>>> + * drm_fb_xrgb8888_to_rgb332 - Convert XRGB8888 to RGB332 clip buffer >>>> + * @dst: RGB332 destination buffer >>>> + * @src: XRGB8888 source buffer >>>> + * @fb: DRM framebuffer >>>> + * @clip: Clip rectangle area to copy >>>> + * >>>> + * Drivers can use this function for RGB332 devices that don't natively support XRGB8888. >>>> + * >>>> + * This function does not apply clipping on dst, i.e. the destination is a small buffer >>>> + * containing the clip rect only. >>>> + */ >>>> +void drm_fb_xrgb8888_to_rgb332(void *dst, void *src, struct drm_framebuffer *fb, >>>> + struct drm_rect *clip) >>>> +{ >>>> + size_t width = drm_rect_width(clip); >>>> + size_t src_len = width * sizeof(u32); >>>> + unsigned int y; >>>> + void *sbuf; >>>> + >>>> + /* Use a buffer to speed up access on buffers with uncached read mapping (i.e. WC) */ >>>> + sbuf = kmalloc(src_len, GFP_KERNEL); >>>> + if (!sbuf) >>>> + return; >>>> + >>>> + src += clip_offset(clip, fb->pitches[0], sizeof(u32)); >>>> + for (y = 0; y < drm_rect_height(clip); y++) { >>>> + memcpy(sbuf, src, src_len); >>>> + drm_fb_xrgb8888_to_rgb332_line(dst, sbuf, width); >>>> + src += fb->pitches[0]; >>>> + dst += width; >>>> + } >>>> + >>>> + kfree(sbuf); >>>> +} >>>> +EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb332); >>>> + >>>> static void drm_fb_xrgb8888_to_rgb565_line(u16 *dbuf, u32 *sbuf, >>>> unsigned int pixels, >>>> bool swab) >>>> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h >>>> index 4e0258a61311..d0809aff5cf8 100644 >>>> --- a/include/drm/drm_format_helper.h >>>> +++ b/include/drm/drm_format_helper.h >>>> @@ -16,6 +16,8 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vadd >>>> struct drm_rect *clip); >>>> void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb, >>>> struct drm_rect *clip, bool cached); >>>> +void drm_fb_xrgb8888_to_rgb332(void *dst, void *vaddr, struct drm_framebuffer *fb, >>>> + struct drm_rect *clip); >>>> void drm_fb_xrgb8888_to_rgb565(void *dst, void *vaddr, >>>> struct drm_framebuffer *fb, >>>> struct drm_rect *clip, bool swab); >>>> -- >>>> 2.32.0 >>>> >>> >