On 7/11/2013 4:18 PM, Fabio Estevam wrote:
On Thu, Jul 11, 2013 at 8:03 PM, Marek Vasut <ma...@denx.de> wrote:
The MX28 multi-layer AHB bus can be too slow and trigger the
FEC DMA too early, before all the data hit the DRAM. This patch
ensures the data are written in the RAM before the DMA starts.
Please see the comment in the patch for full details.
This patch was produced with an amazing help from Albert Aribaud,
who pointed out it can possibly be such a bus synchronisation
issue.
Signed-off-by: Marek Vasut <ma...@denx.de>
Cc: Albert ARIBAUD <albert.u.b...@aribaud.net>
Cc: Fabio Estevam <fabio.este...@freescale.com>
Cc: Stefano Babic <sba...@denx.de>
Excellent, managed to transfer 90MB via TFTP on mx28evk without a
single timeout.
Tested-by: Fabio Estevam <fabio.este...@freescale.com>
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Perhaps this because our memory barriers are lacking.
Linux has this code
asm/io.h:#define writel(v,c) ({ __iowmb();
writel_relaxed(v,c); })
asm/io.h-#ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE
asm/io.h-#include <asm/barrier.h>
asm/io.h-#define __iormb() rmb()
asm/io.h:#define __iowmb() wmb()
asm/io.h-#else
asm/io.h-#define __iormb() do { } while (0)
asm/io.h:#define __iowmb() do { } while (0)
asm/io.h-#endif
asm/io.h-#ifdef CONFIG_ARM_DMA_MEM_BUFFERABLE
asm/io.h-#include <asm/barrier.h>
asm/io.h-#define __iormb() rmb()
asm/io.h:#define __iowmb() wmb()
asm/io.h-#else
asm/io.h-#define __iormb() do { } while (0)
asm/io.h:#define __iowmb() do { } while (0)
asm/io.h-#endif
asm/barrier.h-#elif defined(CONFIG_ARM_DMA_MEM_BUFFERABLE) ||
defined(CONFIG_SMP)
asm/barrier.h-#define mb() do { dsb(); outer_sync(); }
while (0)
asm/barrier.h-#define rmb() dsb()
asm/barrier.h:#define wmb() mb()
asm/barrier.h-#else
asm/barrier.h-#define mb() barrier()
asm/barrier.h-#define rmb() barrier()
asm/barrier.h:#define wmb() barrier()
asm/barrier.h-#endif
asm/barrier.h-#if __LINUX_ARM_ARCH__ >= 7
asm/barrier.h-#define isb() __asm__ __volatile__ ("isb" : : : "memory")
asm/barrier.h:#define dsb() __asm__ __volatile__ ("dsb" : : : "memory")
asm/barrier.h-#define dmb() __asm__ __volatile__ ("dmb" : : : "memory")
asm/barrier.h-#elif defined(CONFIG_CPU_XSC3) || __LINUX_ARM_ARCH__ == 6
asm/barrier.h-#define isb() __asm__ __volatile__ ("mcr p15, 0, %0, c7,
c5, 4" \
asm/barrier.h- : : "r" (0) : "memory")
asm/barrier.h:#define dsb() __asm__ __volatile__ ("mcr p15, 0, %0, c7,
c10, 4" \
asm/barrier.h- : : "r" (0) : "memory")
asm/barrier.h-#define dmb() __asm__ __volatile__ ("mcr p15, 0, %0, c7,
c10, 5" \
_____________________________________
Can you try just adding a dsb() instead of the dummy read?
If this also fixes your problem, it seems better to fix our writel macro
Thanks
Troy
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