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Subject: Re: [PATCH 0/2] Introduce PCI_FIXUP_IOMMU
To:     Joerg Roedel <joro@8bytes.org>
Cc:     Bjorn Helgaas <helgaas@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Hanjun Guo <guohanjun@huawei.com>,
        Sudeep Holla <sudeep.holla@arm.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Len Brown <lenb@kernel.org>,
        jean-philippe <jean-philippe@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        kenneth-lee-2012@foxmail.com, Wangzhou <wangzhou1@hisilicon.com>,
        linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
        iommu@lists.linux-foundation.org, linux-acpi@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org
References: <20200601174104.GA734973@bjorn-Precision-5520>
 <779f4044-cf6a-b0d3-916f-0274450c07d3@linaro.org>
 <20200622115536.GH3701@8bytes.org>
From:   Zhangfei Gao <zhangfei.gao@linaro.org>
Message-ID: <d007cbea-85c0-6c75-fc4a-e2872ff59ea4@linaro.org>
Date:   Tue, 23 Jun 2020 15:48:25 +0800
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Hi, Joerg

On 2020/6/22 下午7:55, Joerg Roedel wrote:
> On Thu, Jun 04, 2020 at 09:33:07PM +0800, Zhangfei Gao wrote:
>> +++ b/drivers/iommu/iommu.c
>> @@ -2418,6 +2418,10 @@ int iommu_fwspec_init(struct device *dev, struct
>> fwnode_handle *iommu_fwnode,
>>          fwspec->iommu_fwnode = iommu_fwnode;
>>          fwspec->ops = ops;
>>          dev_iommu_fwspec_set(dev, fwspec);
>> +
>> +       if (dev_is_pci(dev))
>> +               pci_fixup_device(pci_fixup_final, to_pci_dev(dev));
>> +
> That's not going to fly, I don't think we should run the fixups twice,
> and they should not be run from IOMMU code. Is the only reason for this
> second pass that iommu_fwspec is not yet allocated when it runs the
> first time? I ask because it might be easier to just allocate the struct
> earlier then.
Thanks for looking this.

Yes, it is the only reason calling fixup secondly after iommu_fwspec is 
allocated.

The first time fixup final is very early in pci_bus_add_device.
If allocating iommu_fwspec earlier, it maybe in pci_alloc_dev.
And assigning ops still in iommu_fwspec_init.
Have tested it works.
Not sure is it acceptable?

Alternatively, adding can_stall to struct pci_dev is simple but ugly too,
since pci does not know stall now.


Thanks