From: Zhangfei Gao <zhangfei.gao@linaro.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: jean-philippe <jean-philippe@linaro.org>,
Herbert Xu <herbert@gondor.apana.org.au>,
Arnd Bergmann <arnd@arndb.de>,
linux-pci@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Hanjun Guo <guohanjun@huawei.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
linux-acpi@vger.kernel.org, linux-crypto@vger.kernel.org,
Sudeep Holla <sudeep.holla@arm.com>,
Bjorn Helgaas <bhelgaas@google.com>,
kenneth-lee-2012@foxmail.com,
linux-arm-kernel@lists.infradead.org, Len Brown <lenb@kernel.org>
Subject: Re: [PATCH 0/2] Introduce PCI_FIXUP_IOMMU
Date: Thu, 28 May 2020 14:46:54 +0800 [thread overview]
Message-ID: <83bd3d72-3a0c-d9b6-54ad-5bc0dbc5be7d@linaro.org> (raw)
In-Reply-To: <20200527181842.GA256680@bjorn-Precision-5520>
Hi, Bjorn
On 2020/5/28 上午2:18, Bjorn Helgaas wrote:
> On Tue, May 26, 2020 at 07:49:07PM +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, suggested by Joerg, [1]
> Is this slowdown significant? We already iterate over every device
> when applying PCI_FIXUP_FINAL quirks, so if we used the existing
> PCI_FIXUP_FINAL, we wouldn't be adding a new loop. We would only be
> adding two more iterations to the loop in pci_do_fixups() that tries
> to match quirks against the current device. I doubt that would be a
> measurable slowdown.
I do not notice the difference when compared fixup_iommu and fixup_final
via get_jiffies_64,
since in our platform no other pci fixup is registered.
Here the plan is adding pci_fixup_device in iommu_fwspec_init,
so if using fixup_final the iteration will be done again here.
>
>> For example:
>> Hisilicon platform device need fixup in
>> drivers/pci/quirks.c handling fwspec->can_stall, which is introduced in [2]
>>
>> +static void quirk_huawei_pcie_sva(struct pci_dev *pdev)
>> +{
>> + struct iommu_fwspec *fwspec;
>> +
>> + pdev->eetlp_prefix_path = 1;
>> + fwspec = dev_iommu_fwspec_get(&pdev->dev);
>> + if (fwspec)
>> + fwspec->can_stall = 1;
>> +}
>> +
>> +DECLARE_PCI_FIXUP_IOMMU(PCI_VENDOR_ID_HUAWEI, 0xa250, quirk_huawei_pcie_sva);
>> +DECLARE_PCI_iFIXUP_IOMMU(PCI_VENDOR_ID_HUAWEI, 0xa251, quirk_huawei_pcie_sva);
>>
>> [1] https://www.spinics.net/lists/iommu/msg44591.html
>> [2] https://www.spinics.net/lists/linux-pci/msg94559.html
> If you reference these in the commit logs, please use lore.kernel.org
> links instead of spinics.
Got it, thanks Bjorn.
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next prev parent reply other threads:[~2020-05-28 6:47 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-26 11:49 [PATCH 0/2] Introduce PCI_FIXUP_IOMMU Zhangfei Gao
2020-05-26 11:49 ` [PATCH 1/2] PCI: " Zhangfei Gao
2020-05-26 14:46 ` Christoph Hellwig
2020-05-26 15:09 ` Zhangfei Gao
2020-05-27 9:01 ` Greg Kroah-Hartman
2020-05-26 11:49 ` [PATCH 2/2] iommu: calling pci_fixup_iommu in iommu_fwspec_init Zhangfei Gao
2020-05-27 9:01 ` Greg Kroah-Hartman
2020-05-28 6:53 ` Zhangfei Gao
2020-05-27 9:00 ` [PATCH 0/2] Introduce PCI_FIXUP_IOMMU Greg Kroah-Hartman
2020-05-27 9:53 ` Arnd Bergmann
2020-05-27 13:51 ` Zhangfei Gao
2020-05-27 18:18 ` Bjorn Helgaas
2020-05-28 6:46 ` Zhangfei Gao [this message]
2020-05-28 7:33 ` Joerg Roedel
2020-06-01 17:41 ` Bjorn Helgaas
2020-06-04 13:33 ` Zhangfei Gao
2020-06-05 23:19 ` Bjorn Helgaas
2020-06-08 2:54 ` Zhangfei Gao
2020-06-08 16:41 ` Bjorn Helgaas
2020-06-09 4:01 ` Zhangfei Gao
2020-06-09 9:15 ` Arnd Bergmann
2020-06-09 16:49 ` Bjorn Helgaas
2020-06-11 2:54 ` Zhangfei Gao
2020-06-11 13:44 ` Bjorn Helgaas
2020-06-13 14:30 ` Zhangfei Gao
2020-06-15 23:52 ` Bjorn Helgaas
2020-06-19 2:26 ` Zhangfei Gao
2020-06-23 15:04 ` Bjorn Helgaas
2020-12-16 11:24 ` Zhou Wang
2020-12-17 20:38 ` Bjorn Helgaas
2021-01-12 7:05 ` zhangfei.gao
2020-06-22 11:55 ` Joerg Roedel
2020-06-23 7:48 ` Zhangfei Gao
2020-06-22 11:53 ` Joerg Roedel
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