Re: using DMA-API on ARM

[Arend van Spriel]

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

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