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.
> 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()?
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
>>
>
