linux-kernel - Re: [PATCH 4/5] iommu/tegra-smmu: Add PCI support

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Message-ID: <20200928223301.GB4816@Asurada-Nvidia>
Date:   Mon, 28 Sep 2020 15:33:01 -0700
From:   Nicolin Chen <nicoleotsuka@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     joro@...tes.org, krzk@...nel.org, vdumpa@...dia.com,
        jonathanh@...dia.com, linux-tegra@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] iommu/tegra-smmu: Add PCI support

On Mon, Sep 28, 2020 at 09:55:45AM +0200, Thierry Reding wrote:
> On Sat, Sep 26, 2020 at 01:07:18AM -0700, Nicolin Chen wrote:
> > +#ifdef CONFIG_PCI
> > +	if (!iommu_present(&pci_bus_type)) {
> > +		pci_request_acs();
> > +		err = bus_set_iommu(&pci_bus_type, &tegra_smmu_ops);
> > +		if (err < 0) {
> > +			bus_set_iommu(&platform_bus_type, NULL);
> > +			iommu_device_unregister(&smmu->iommu);
> > +			iommu_device_sysfs_remove(&smmu->iommu);
> > +			return ERR_PTR(err);
> 
> It might be worth factoring out the cleanup code now that there are
> multiple failures from which we may need to clean up.

Will do.

> Also, it'd be great if somehow we could do this without the #ifdef,
> but I guess since we're using the pci_bus_type global variable directly,
> there isn't much we can do here?

Probably no -- both pci_bus_type and pci_request_acs seem to depend
on it.