Re: [PATCH 0/2] Let pci_fixup_final access iommu_fwnode

[Joerg Roedel]

On Tue, May 12, 2020 at 12:08:29PM +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.
> 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);

I don't think it is a great idea to hook this into PCI_FIXUP_FINAL. The
fixup list needs to be processed for every device, which will slow down
probing.

So either we introduce something like PCI_FIXUP_IOMMU, if this is
entirely PCI specific. If it needs to be generic we need some fixup
infrastructure in the IOMMU code itself.

Regards,

	Joerg