linux-kernel - Re: [PATCH 08/11] iommu/msm: Make use of iommu_device

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Message-ID: <20170210153339.GK7339@8bytes.org>
Date:   Fri, 10 Feb 2017 16:33:40 +0100
From:   Joerg Roedel <joro@...tes.org>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Will Deacon <will.deacon@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Alex Williamson <alex.williamson@...hat.com>,
        David Woodhouse <dwmw2@...radead.org>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH 08/11] iommu/msm: Make use of iommu_device_register
 interface

On Fri, Feb 10, 2017 at 02:35:39PM +0000, Robin Murphy wrote:
> On 09/02/17 11:32, Joerg Roedel wrote:
> > +	ret = iommu_device_sysfs_add(&iommu->iommu, iommu->dev, NULL,
> > +				     "msm-smmu.%pa", &ioaddr);
> > +	if (ret) {
> > +		pr_err("Could not add msm-smmu at %pa to sysfs\n", &ioaddr);
> > +		goto fail;
> > +	}
> 
> Nit: there's a bit of inconsistency with printing errors between the
> various drivers (for both _sysfs_add and _register). I reckon if we want
> error messages we may as well just fold them into the helper functions.

Yeah, this could be unified too. For now I looked how verbose the
driver was that I was going to change and added messages to be
consistent inside the drivers.

> 
> > +
> > +	iommu_device_set_ops(&iommu->iommu, &msm_iommu_ops);
> > +	iommu_device_set_fwnode(&iommu->iommu, &pdev->dev.of_node->fwnode);
> > +
> > +	ret = iommu_device_register(&iommu->iommu);
> > +	if (ret) {
> > +		pr_err("Could not register msm-smmu at %pa\n", &ioaddr);
> > +		goto fail;
> > +	}
> 
> I think there's a corresponding unregister missing for
> msm_iommu_remove() here (and similarly in the ARM SMMU drivers, looking
> back). I know it's not strictly a problem at the moment, but I do now
> have IOMMU-drivers-as-modules working on top of the probe deferral
> series... ;)

Well, that there was an iommu_register_instance() without any
unregistration interface at all makes me believe that unregistering
iommus is not really implemented yet.

And in fact, the remove functions for msm and arm-smmu seem to only
disable the hardware, but are not removing the corresponding data
structures.

So I think we are fine from that side.


	Joerg