From mboxrd@z Thu Jan  1 00:00:00 1970
From: Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH v2 1/2] iommu: add support for drivers that manage iommu
 explicitly
Date: Tue, 10 Sep 2019 10:14:15 +0200
Message-ID: <20190910081415.GB3247@8bytes.org>
References: <20190906214409.26677-1-robdclark@gmail.com>
 <20190906214409.26677-2-robdclark@gmail.com>
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To: Rob Clark <robdclark@gmail.com>
Cc: iommu@lists.linux-foundation.org, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, Robin Murphy <robin.murphy@arm.com>, Will Deacon <will@kernel.org>, Rob Clark <robdclark@chromium.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>, Andrew Morton <akpm@linux-foundation.org>, Suzuki K Poulose <suzuki.poulose@arm.com>, Rasmus Villemoes <linux@rasmusvillemoes.dk>, Heikki Krogerus <heikki.krogerus@linux.intel.com>, Bartosz Golaszewski <brgl@bgdev.pl>, Sudeep Holla <sudeep.holla@arm.com>, Joe Perches <joe@perches.com>, Arnd Bergmann <arnd@arndb.de>, open list <linux-kernel@vger.kernel.org>
List-Id: dri-devel@lists.freedesktop.org

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?

Regards,

	Joerg