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Re: [RFC PATCH v3 5/6] dt-bindings: of: Add restricted DMA pool

On Fri, Jan 8, 2021 at 2:15 AM Florian Fainelli <f.fainelli@xxxxxxxxx> wrote:
> On 1/7/21 10:00 AM, Konrad Rzeszutek Wilk wrote:
> >>>
> >>>
> >>>  - Nothing stops the physical device from bypassing the SWIOTLB buffer.
> >>>    That is if an errant device screwed up the length or DMA address, the
> >>>    SWIOTLB would gladly do what the device told it do?
> >>
> >> So the system needs to provide a way to lock down the memory access, e.g. 
> >> MPU.
> >
> > OK! Would it be prudent to have this in the description above perhaps?
> Yes this is something that must be documented as a requirement for the
> restricted DMA pool users, otherwise attempting to do restricted DMA
> pool is no different than say, using a device private CMA region.
> Without the enforcement, this is just a best effort.

Will add in the next version.

> --
> Florian



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