Gabe Black (gabeblack@chromium.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/3668
-gerrit
commit 939611002e4ac8468d7eab6e397348d2fc3d3bae Author: Stefan Reinauer reinauer@chromium.org Date: Mon May 20 15:24:13 2013 -0700
exynos5420: 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: I960f87a370e97f9e91236ad796d931573bb3dbb8 Signed-off-by: Stefan Reinauer reinauer@chromium.org Signed-off-by: Gabe Black gabeblack@chromium.org --- src/cpu/samsung/exynos5420/cpu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/cpu/samsung/exynos5420/cpu.c b/src/cpu/samsung/exynos5420/cpu.c index 1d51174..6e360bf 100644 --- a/src/cpu/samsung/exynos5420/cpu.c +++ b/src/cpu/samsung/exynos5420/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); }