Hi
Am 26.03.25 um 11:53 schrieb Jani Nikula:
On Tue, 25 Mar 2025, Thomas Zimmermann <tzimmerm...@suse.de> wrote:
For ease of implementation, existing line-conversion functions
for 16-bit formats write each pixel individually. Optimize the
performance by writing mulitple pixels in single 64-bit and 32-bit
stores.
Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
---
drivers/gpu/drm/drm_format_helper.c | 40 ++++++++++++++++++++++++++++-
1 file changed, 39 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_format_helper.c
b/drivers/gpu/drm/drm_format_helper.c
index b9c9c712aa9c..66137df85725 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -262,10 +262,48 @@ static __always_inline void drm_fb_xfrm_line_32to16(void
*dbuf, const void *sbuf
unsigned int pixels,
u32 (*xfrm_pixel)(u32))
{
- __le16 *dbuf16 = dbuf;
+ __le64 *dbuf64 = dbuf;
+ __le32 *dbuf32;
+ __le16 *dbuf16;
const __le32 *sbuf32 = sbuf;
const __le32 *send32 = sbuf32 + pixels;
+#if defined(CONFIG_64BIT)
+ /* write 4 pixels at once */
+ send32 -= pixels & GENMASK(1, 0);
+ while (sbuf32 < send32) {
I find the adjusting of send32 before and after the loop with different
masks a bit confusing. Would it not suffice to:
while (sbuf32 < ALIGN_DOWN(send32, 4))
and leave send32 untouched? With different alignments for 2 pixels at a
time.
Makes sense.
Best regards
Thomas
BR,
Jani.
+ u32 pix[4] = {
+ le32_to_cpup(sbuf32++),
+ le32_to_cpup(sbuf32++),
+ le32_to_cpup(sbuf32++),
+ le32_to_cpup(sbuf32++),
+ };
+ /* write output bytes in reverse order for little endianness */
+ u64 val64 = ((u64)xfrm_pixel(pix[0])) |
+ ((u64)xfrm_pixel(pix[1]) << 16) |
+ ((u64)xfrm_pixel(pix[2]) << 32) |
+ ((u64)xfrm_pixel(pix[3]) << 48);
+ *dbuf64++ = cpu_to_le64(val64);
+ }
+ send32 += pixels & GENMASK(1, 1);
+#endif
+
+ /* write 2 pixels at once */
+ dbuf32 = (__le32 __force *)dbuf64;
+ while (sbuf32 < send32) {
+ u32 pix[2] = {
+ le32_to_cpup(sbuf32++),
+ le32_to_cpup(sbuf32++),
+ };
+ /* write output bytes in reverse order for little endianness */
+ u32 val32 = xfrm_pixel(pix[0]) |
+ (xfrm_pixel(pix[1]) << 16);
+ *dbuf32++ = cpu_to_le32(val32);
+ }
+ send32 += pixels & GENMASK(0, 0);
+
+ /* write trailing pixel */
+ dbuf16 = (__le16 __force *)dbuf32;
while (sbuf32 < send32)
*dbuf16++ = cpu_to_le16(xfrm_pixel(le32_to_cpup(sbuf32++)));
}
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
