[U-Boot] [RFC] 0/4] Add Pl330 DMA support

Dinh Nguyen
2016-10-14T22:10:57Z

On 10/10/2016 10:52 AM, Dinh Nguyen wrote:
> Hi,
>
> This patchset adds the PL330 DMA driver to U-Boot. The SoCFPGA platform makes
> use of the PL330 to transfer zereos to the SDRAM which enables the ECC bit.
>
> This is only an RFC because after rebasing to v2016.11-rc1, I had to revert
> the following patch "a78cd8613204 ARM: Rework and correct barrier definitions"
> in order for this patch set to work correctly. With the above patch applied,
> after the SDRAM scrubbing is complete, the SPL is failing to find the MMC
> device.
>

I kinda figured out why patch "a78cd8613204 ARM: Rework and correct
barrier definitions" is causing SPL to fail after the SDRAM scrub
operation. It appears that before the above mentioned patch, the dmb()
operation is defined as this:

#define dmb() __asm__ __volatile__ ("" : : : "memory")

after the patch, the dmb is now:

#define DMB asm volatile ("dmb sy" : : : "memory")

So the "dmb sy" as described in the ARM documentation is a "Full system
DMB operation". For whatever reason, this change is causing the SPL
error after the SDRAM scrub operation.

Dinh