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From: Rob Clark <robdclark@gmail.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: Rob Clark <robdclark@chromium.org>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	Bartosz Golaszewski <brgl@bgdev.pl>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Robin Murphy <robin.murphy@arm.com>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Sudeep Holla <sudeep.holla@arm.com>,
	"list@263.net:IOMMU DRIVERS <iommu@lists.linux-foundation.org>,
	Joerg Roedel <joro@8bytes.org>,
	" <iommu@lists.linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Joe Perches <joe@perches.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will@kernel.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/2] iommu: add support for drivers that manage iommu explicitly
Date: Tue, 10 Sep 2019 08:34:13 -0700
Message-ID: <CAF6AEGsFmuO5M_RWm-RjDT_F_1Z=MLYmNqRXqFNDR7aUoPaMdg@mail.gmail.com> (raw)
In-Reply-To: <20190910081415.GB3247@8bytes.org>

On Tue, Sep 10, 2019 at 1:14 AM Joerg Roedel <joro@8bytes.org> wrote:
>
> On Fri, Sep 06, 2019 at 02:44:01PM -0700, Rob Clark wrote:
> > @@ -674,7 +674,7 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev)
> >
> >       mutex_lock(&group->mutex);
> >       list_add_tail(&device->list, &group->devices);
> > -     if (group->domain)
> > +     if (group->domain && !(dev->driver && dev->driver->driver_manages_iommu))
>
> Hmm, this code usually runs at enumeration time when no driver is
> attached to the device. Actually it would be pretty dangerous when this
> code runs while a driver is attached to the device. How does that change
> make things work for you?
>

I was seeing this get called via the path driver_probe_device() ->
platform_dma_configure() -> of_dma_configure() -> of_iommu_configure()
-> iommu_probe_device() -> ...

The only cases I was seeing where dev->driver is NULL where a few
places that drivers call of_dma_configure() on their own sub-devices.
But maybe there are some other paths that I did not notice?

BR,
-R
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Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-06 21:44 [PATCH v3 0/2] iommu: handle drivers that manage iommu directly Rob Clark
2019-09-06 21:44 ` [PATCH v2 1/2] iommu: add support for drivers that manage iommu explicitly Rob Clark
2019-09-10  8:14   ` Joerg Roedel
2019-09-10 15:34     ` Rob Clark [this message]
2019-09-10 16:51       ` Robin Murphy
2019-09-06 21:44 ` [PATCH v2 2/2] drm/msm: mark devices where iommu is managed by driver Rob Clark
2019-09-10 16:34 ` [PATCH v3 0/2] iommu: handle drivers that manage iommu directly Robin Murphy
2019-09-10 17:10   ` Rob Clark
2019-09-17 13:36     ` Will Deacon

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