[PATCH 2/3] video: stm: allocate uncached framebuffer memory as write-combine

Ahmad Fatoum a.fatoum at barebox.org
Fri Nov 7 13:00:30 PST 2025


For i.MX23 and i.MX28, this makes no difference as the MMU treats
write-combine and uncached the same on ARMv6 and earlier, but on
ARMv7 and above, use of the write combine buffer allows us to spend less
time pushing pixels.

Signed-off-by: Ahmad Fatoum <a.fatoum at barebox.org>
---
 drivers/video/stm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/stm.c b/drivers/video/stm.c
index c5dadb823251..da006b7c240f 100644
--- a/drivers/video/stm.c
+++ b/drivers/video/stm.c
@@ -305,8 +305,8 @@ static int stmfb_activate_var(struct fb_info *fb_info)
 		remap_range(fbi->fixed_screen,
 				fbi->fixed_screen_size, MAP_UNCACHED);
 	} else {
-		fb_info->screen_base = dma_alloc_coherent(DMA_DEVICE_BROKEN,
-							  size, DMA_ADDRESS_BROKEN);
+		fb_info->screen_base = dma_alloc_writecombine(DMA_DEVICE_BROKEN,
+							      size, DMA_ADDRESS_BROKEN);
 		if (!fb_info->screen_base)
 			return -ENOMEM;
 		fbi->memory_size = size;
-- 
2.47.3




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