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drm/format-helper: Optimize 32-to-24-bpp conversion

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For ease of implementation, existing line-conversion functions
for 24-bit formats write each byte individually. Optimize the
performance by writing 4 pixels in 3 32-bit stores.

v2:
- simplify address calculation (Jani)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250328141709.217283-7-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann 2025-03-28 15:15:02 +01:00
parent a376dcf49c
commit 58523a25cb
1 changed files with 36 additions and 1 deletions
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37
drivers/gpu/drm/drm_format_helper.c
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@ -246,6 +246,9 @@ static int drm_fb_xfrm(struct iosys_map *dst,
xfrm_line);
}
#define ALIGN_DOWN_PIXELS(end, n, a) \
((end) - ((n) & ((a) - 1)))
static __always_inline void drm_fb_xfrm_line_32to8(void *dbuf, const void *sbuf,
unsigned int pixels,
u32 (*xfrm_pixel)(u32))
@ -274,10 +277,42 @@ static __always_inline void drm_fb_xfrm_line_32to24(void *dbuf, const void *sbuf
unsigned int pixels,
u32 (*xfrm_pixel)(u32))
{
u8 *dbuf8 = dbuf;
__le32 *dbuf32 = dbuf;
u8 *dbuf8;
const __le32 *sbuf32 = sbuf;
const __le32 *send32 = sbuf32 + pixels;
/* write pixels in chunks of 4 */
while (sbuf32 < ALIGN_DOWN_PIXELS(send32, pixels, 4)) {
u32 val24[4] = {
xfrm_pixel(le32_to_cpup(sbuf32++)),
xfrm_pixel(le32_to_cpup(sbuf32++)),
xfrm_pixel(le32_to_cpup(sbuf32++)),
xfrm_pixel(le32_to_cpup(sbuf32++)),
};
u32 out32[3] = {
/* write output bytes in reverse order for little endianness */
((val24[0] & 0x000000ff)) |
((val24[0] & 0x0000ff00)) |
((val24[0] & 0x00ff0000)) |
((val24[1] & 0x000000ff) << 24),
((val24[1] & 0x0000ff00) >> 8) |
((val24[1] & 0x00ff0000) >> 8) |
((val24[2] & 0x000000ff) << 16) |
((val24[2] & 0x0000ff00) << 16),
((val24[2] & 0x00ff0000) >> 16) |
((val24[3] & 0x000000ff) << 8) |
((val24[3] & 0x0000ff00) << 8) |
((val24[3] & 0x00ff0000) << 8),
};
*dbuf32++ = cpu_to_le32(out32[0]);
*dbuf32++ = cpu_to_le32(out32[1]);
*dbuf32++ = cpu_to_le32(out32[2]);
}
/* write trailing pixel */
dbuf8 = (u8 __force *)dbuf32;
while (sbuf32 < send32) {
u32 val24 = xfrm_pixel(le32_to_cpup(sbuf32++));
/* write output in reverse order for little endianness */