Re: [PATCH v3 0/4] PCI: get DMA configuration from parent device

[Murali Karicheri]

On 01/08/2015 05:27 PM, Arnd Bergmann wrote:
> On Thursday 08 January 2015 09:56:39 Arnd Bergmann wrote:
> > There is another interesting case, which is a USB host controller or
> > something similar behind a PCI bus. These are quite common and also
> > need to be handled in some form. Let's do just PCI first for now, but
> > be aware that this will come next. Should we assume that the ID that
> > is required for a device is either known from the device node, or
> > that it comes from a PCI device? That means for the USB case, we will
> > likely need to have some custom logic. There seems to be an implicit
> > assumption all over the kernel that all devices have the same IOMMU
> > instance, but we can't really rely on that here.
>
> Update: I've checked the USB implementation and we are lucky because
> these interactions are all done by the USB host controller, and a
> USB device is not itself DMA capable. We don't have to do anything
> for USB.

Ok Thanks.

Murali
> 	Arnd
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Murali Karicheri
Linux Kernel, Texas Instruments
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