[U-Boot] [PATCH v3 03/10] sunxi: Remove mmc DMA support

Hans de Goede
2014-07-26T13:07:08Z

Hi,

On 07/23/2014 07:35 PM, Siarhei Siamashka wrote:
> On Mon, 9 Jun 2014 11:36:55 +0200
> Hans de Goede <hdegoede@redhat.com> wrote:
>
>> The DMA code in sunxi_mmc.c is broken. mmc_trans_data_by_dma() allocates the
>> dma descriptors on the stack, and then exits while the dma transfer is in
>> progress, so the dma engine is reading stack memory which at that point may
>> be re-used. So far we've gotten away with this by luck, but recent u-boot
>> changes have shifted the stack start address by 16 bytes, which combined
>> with dma alignment now exposes this problem.
>>
>> Since we end up just busy waiting for the dma engine anyway, this commit
>> fixes things by simply removing the dma code, resulting in smaller bug-free
>> code.
>>
>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
>> Acked-by: Ian Campbell <ijc@hellion.org.uk>
>
> Acked-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>

Thanks for the review. Note Ian has already submitted a pull-request
for these patches, so your ack won't make it upstream.

> Was it a good idea to keep v2014.07 release relying on luck without
> this patch?

Considering that things just work there, and the timing of when I found
this out, yes.

Regards,

Hans