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exynos5250: Clear the framebuffer before making it uncacheable.

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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.

BUG=None
TEST=Built and booted on Snow. Verified that graphics were drawn completely.
BRANCH=None

Change-Id: I94c81145b422eb440c7698273e7f3944c5ee486e
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://gerrit.chromium.org/gerrit/55640
Commit-Queue: Stefan Reinauer <reinauer@google.com>
Reviewed-by: Stefan Reinauer <reinauer@google.com>
Tested-by: Stefan Reinauer <reinauer@google.com>
This commit is contained in:
Gabe Black 2013-05-18 23:06:47 -07:00 • committed by ChromeBot
commit 0df1b1c36f
1 changed files with 2 additions and 1 deletions
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3
src/cpu/samsung/exynos5250/cpu.c
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@ -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);
}