Re: using DMA-API on ARM

Arend van Spriel
2014-12-09T11:07:33Z

On 12/09/14 11:29, Russell King - ARM Linux wrote:
> On Tue, Dec 09, 2014 at 11:19:40AM +0100, Arend van Spriel wrote:
>> The issue did not trigger overnight so it seems setting bit 22<Shared
>> Attribute _Override_ Enable> solves the issue over here. Now the question is
>> how to move forward with this. As I understood from Catalin this patch was
>> not included as it was not considered responsibility of the linux kernel.
>
> It is preferable for firmware to configure the L2 cache appropriately,
> which includes things like the prefetch offsets as well as feature bits
> like bit 22.
>
> I think what I'll do is queue up a patch which adds a warning if bit 22
> is not set, suggesting that firmware is updated to set this bit.

I was thinking in the same direction. Thanks to you all for looking into
this. It did not feel right to use the dma_sync_single_for_cpu() for
memory allocated with dma_alloc_coherent() and I am glad this got
cleared up.

Regards,
Arend