Gabe Black (gabeblack@chromium.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/3655
-gerrit
commit d73f0ef52adc1e8f4094c61d671e8b1ed6d0a47f Author: Gabe Black gabeblack@google.com Date: Sat May 18 23:06:47 2013 -0700
exynos5250: Clear the framebuffer before making it uncacheable.
If we clear the framebuffer and then flush it back to memory using cache operations, the writes are going to be full cachelines at a time. If we make it uncacheable first, the writes will be serialized writes of whatever sized chunks memset uses, probably 4 bytes or less.
Change-Id: I1b81731cfed00ae091ba6357451ab186d16f559e Signed-off-by: Gabe Black gabeblack@chromium.org --- src/cpu/samsung/exynos5250/cpu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/cpu/samsung/exynos5250/cpu.c b/src/cpu/samsung/exynos5250/cpu.c index d2a6df7..3687ea8 100644 --- a/src/cpu/samsung/exynos5250/cpu.c +++ b/src/cpu/samsung/exynos5250/cpu.c @@ -97,6 +97,8 @@ static void exynos_displayport_init(device_t dev) lcdbase = (uintptr_t)cbmem_add(CBMEM_ID_CONSOLE, fb_size); printk(BIOS_SPEW, "LCD framebuffer base is %p\n", (void *)(lcdbase));
+ memset((void *)lcdbase, 0, fb_size); /* clear the framebuffer */ + /* * We need to clean and invalidate the framebuffer region and disable * caching as well. We assume that our dcache <--> memory address @@ -114,7 +116,6 @@ static void exynos_displayport_init(device_t dev) mmio_resource(dev, 1, lcdbase/KiB, (fb_size + KiB - 1)/KiB); printk(BIOS_DEBUG, "Initializing Exynos VGA, base %p\n", (void *)lcdbase); - memset((void *)lcdbase, 0, fb_size); /* clear the framebuffer */ ret = lcd_ctrl_init(fb_size, &panel, (void *)lcdbase); }