Re: Remoteproc: Translating between host and device addresses.

From: Ohad Ben-Cohen
Date: Mon Sep 10 2012 - 08:49:13 EST

Hi Sjur,

On Tue, Aug 14, 2012 at 8:06 PM, Sjur BRENDELAND
<sjur.brandeland@xxxxxxxxxxxxxx> wrote:
> One way for the device to figure out the translation between
> host-physical and device-address is to peek into some CarveOut
> resource entry and compute this translation. Because a CarveOut
> resource entry contains both the host-physical-address and the
> device address for the same memory location. But this feels
> like a workaround, shouldn't we make a more explicit way of
> communicating this mapping between host-physical and device
> addresses?

Yes, we should. The plan is, when relevant, to switch to the
IOMMU-based DMA API to allocate device addresses (by programming the
IOMMUs automatically), and stop sending physical addresses remotely.

For OMAP, btw, we will still provide those device->physical
translation resource entries, because OMAP4 has a few remote
components that access the host-physical memory directly.

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