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Subject: Re: [PATCH 1/2] PCI: Introduce PCI_FIXUP_IOMMU
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Joerg Roedel <joro@8bytes.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-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org, iommu@lists.linux-foundation.org,
        linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org
References: <1590493749-13823-1-git-send-email-zhangfei.gao@linaro.org>
 <1590493749-13823-2-git-send-email-zhangfei.gao@linaro.org>
 <20200526144644.GA20784@infradead.org>
From:   Zhangfei Gao <zhangfei.gao@linaro.org>
Message-ID: <39144dc0-3b04-3127-978b-bd8487dd06e0@linaro.org>
Date:   Tue, 26 May 2020 23:09:57 +0800
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Hi, Christoph

On 2020/5/26 下午10:46, Christoph Hellwig wrote:
> On Tue, May 26, 2020 at 07:49:08PM +0800, Zhangfei Gao wrote:
>> Some platform devices appear as PCI but are actually on the AMBA bus,
>> and they need fixup in drivers/pci/quirks.c handling iommu_fwnode.
>> Here introducing PCI_FIXUP_IOMMU, which is called after iommu_fwnode
>> is allocated, instead of reusing PCI_FIXUP_FINAL since it will slow
>> down iommu probing as all devices in fixup final list will be
>> reprocessed.
> Who is going to use this?  I don't see a single user in the series.
We will add iommu fixup in drivers/pci/quirks.c, handling

fwspec->can_stall, which is introduced in

https://www.spinics.net/lists/linux-pci/msg94559.html

Unfortunately, the patch does not catch v5.8, so we have to wait.
And we want to check whether this is a right method to solve this issue.

Thanks