linux-kernel - Re: [PATCH 0/2] Let pci_fixup_final access iommu

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Date:   Fri, 22 May 2020 10:13:11 +0800
From:   Zhangfei Gao <zhangfei.gao@...aro.org>
To:     Joerg Roedel <joro@...tes.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Hanjun Guo <guohanjun@...wei.com>,
        Sudeep Holla <sudeep.holla@....com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        jean-philippe <jean-philippe@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        kenneth-lee-2012@...mail.com, Wangzhou <wangzhou1@...ilicon.com>
Cc:     linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-acpi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/2] Let pci_fixup_final access iommu_fwnode

Hi, Joerg

On 2020/5/12 下午12:08, 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.
> So calling pci_fixup_final after iommu_fwnode is allocated.
>
> For example:
> Hisilicon platform device need fixup in
> drivers/pci/quirks.c
>
> +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_FINAL(PCI_VENDOR_ID_HUAWEI, 0xa250, quirk_huawei_pcie_sva);
> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0xa251, quirk_huawei_pcie_sva);
>   
>
> Zhangfei Gao (2):
>    iommu/of: Let pci_fixup_final access iommu_fwnode
>    ACPI/IORT: Let pci_fixup_final access iommu_fwnode
>
>   drivers/acpi/arm64/iort.c | 1 +
>   drivers/iommu/of_iommu.c  | 1 +
>   2 files changed, 2 insertions(+)
>
Would you mind give any suggestion?

We need access fwspec->can_stall describing the platform device (a fake 
pcie) can support stall feature.
can_stall will be used arm_smmu_add_device [1].
And stall is not a pci feature, so no such member in struct pci_dev.

iommu_fwnode is allocated in iommu_fwspec_init, from of_pci_iommu_init 
or iort_pci_iommu_init.
The pci_fixup_device(pci_fixup_final, dev) in pci_bus_add_device is too 
early that  iommu_fwnode
is not allocated.
The pci_fixup_device(pci_fixup_enable, dev) in do_pci_enable_device is 
too late after

arm_smmu_add_device.


So the idea here is calling pci_fixup_device(pci_fixup_final) after
of_pci_iommu_init and iort_pci_iommu_init, where iommu_fwnode is allocated.



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

Thanks