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sunxi: mctl_mem_matches: Add missing memory barrier 

We are running with the caches disabled when mctl_mem_matches gets called,
but the cpu's write buffer is still there and can still get in the way,
add a memory barrier to fix this.

This avoids mctl_mem_matches always returning false in some cases, which
was resulting in:

U-Boot SPL 2015.07 (Apr 14 2016 - 18:47:26)
DRAM: 1024 MiB

U-Boot 2015.07 (Apr 14 2016 - 18:47:26 +0200) Allwinner Technology

CPU:   Allwinner A23 (SUN8I)
DRAM:  512 MiB

Where 512 MiB is the right amount, but the DRAM controller would be
initialized for 1024 MiB.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>
This commit is contained in:
Hans de Goede 2016-04-14 18:53:32 +02:00
parent e25b369c04
commit bfb33f0bc4
1 changed files with 2 additions and 0 deletions
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2
arch/arm/mach-sunxi/dram_helpers.c
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@ -7,6 +7,7 @@
*/ */
#include <common.h> #include <common.h>
#include <asm/armv7.h>
#include <asm/io.h> #include <asm/io.h>
#include <asm/arch/dram.h> #include <asm/arch/dram.h>
@ -31,6 +32,7 @@ bool mctl_mem_matches(u32 offset)
/* Try to write different values to RAM at two addresses */ /* Try to write different values to RAM at two addresses */
writel(0, CONFIG_SYS_SDRAM_BASE); writel(0, CONFIG_SYS_SDRAM_BASE);
writel(0xaa55aa55, (ulong)CONFIG_SYS_SDRAM_BASE + offset); writel(0xaa55aa55, (ulong)CONFIG_SYS_SDRAM_BASE + offset);
DSB;
/* Check if the same value is actually observed when reading back */ /* Check if the same value is actually observed when reading back */
return readl(CONFIG_SYS_SDRAM_BASE) == return readl(CONFIG_SYS_SDRAM_BASE) ==
readl((ulong)CONFIG_SYS_SDRAM_BASE + offset); readl((ulong)CONFIG_SYS_SDRAM_BASE + offset);