linux-kernel - Re: [PATCH 2/2] iommu/omap: Add support to program multiple iommus

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Date:   Fri, 1 Sep 2017 12:01:41 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Suman Anna <s-anna@...com>
Cc:     iommu@...ts.linux-foundation.org, Tony Lindgren <tony@...mide.com>,
        Tero Kristo <t-kristo@...com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] iommu/omap: Add support to program multiple iommus

Hi Suman,

On Thu, Aug 31, 2017 at 08:14:02AM -0500, Suman Anna wrote:
> The OMAP IOMMU driver has been enhanced to support allowing
> multiple IOMMUs to be programmed by a single client user. This
> support is being added mainly to handle the DSP subsystems on
> the DRA7xx SoCs, which have two MMUs within the same subsystem.
> These MMUs provide translations to a processor core port and
> an internal EDMA port. This support allows both the MMUs to
> be programmed together, but with each one retaining it's own
> internal state objects. The internal EDMA is managed by the
> software running on the DSPs, and this design provides on-par
> functionality with previous generation OMAP DSPs where the
> EDMA and the DSP core shared the same MMU.

I didn't get that from the review, so a question here: Do both MMUs show
show up in sysfs, means, do you register both of them the the core code?

Because I think with the solution implemented here, only a single,
combined MMU should be visible to iommu core code and in sysfs.


Regards,

	Joerg