On Tue, Jan 12, 2021 at 02:49:52PM +0800, Zhangfei Gao wrote: > HiSilicon KunPeng920 and KunPeng930 have devices appear as PCI but are > actually on the AMBA bus. These fake PCI devices can not support tlp > and have to enable SMMU stall mode to use the SVA feature. > > Add a quirk to set dma-can-stall property and enable tlp for these devices. s/tlp/TLP/ I don't think "enable TLP" really captures what's going on here. You must be referring to the fact that you set pdev->eetlp_prefix_path. That is normally set by pci_configure_eetlp_prefix() if the Device Capabilities 2 register has the End-End TLP Prefix Supported bit set *and* all devices in the upstream path also have it set. The only place we currently test eetlp_prefix_path is in pci_enable_pasid(). In PCIe, PASID is implemented using the PASID TLP prefix, so we only enable PASID if TLP prefixes are supported. If I understand correctly, a PASID-like feature is implemented on AMBA without using TLP prefixes, and setting eetlp_prefix_path makes that work. I don't think you should do this by setting eetlp_prefix_path because TLP prefixes are used for other features, e.g., TPH. Setting eetlp_prefix_path implies these devices can also support things like TLP, and I don't think that's necessarily true. Apparently these devices have a PASID capability. I think you should add a new pci_dev bit that is specific to this idea of "PASID works without TLP prefixes" and then change pci_enable_pasid() to look at that bit as well as eetlp_prefix_path. It seems like dma-can-stall is a separate thing from PASID? If so, this should be two separate patches. If they can be separated, I would probably make the PASID thing the first patch, and then the "dma-can-stall" can be on its own as a broken DT workaround (if that's what it is) and it's easier to remove that if it become obsolete. > Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx> > Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx> > Signed-off-by: Zhou Wang <wangzhou1@xxxxxxxxxxxxx> > --- > Property dma-can-stall depends on patchset > https://lore.kernel.org/linux-iommu/20210108145217.2254447-1-jean-philippe@xxxxxxxxxx/ > > drivers/pci/quirks.c | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > index 653660e..a27f327 100644 > --- a/drivers/pci/quirks.c > +++ b/drivers/pci/quirks.c > @@ -1825,6 +1825,31 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_E7525_MCH, quir > > DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_VENDOR_ID_HUAWEI, 0x1610, PCI_CLASS_BRIDGE_PCI, 8, quirk_pcie_mch); > > +static void quirk_huawei_pcie_sva(struct pci_dev *pdev) > +{ > + struct property_entry properties[] = { > + PROPERTY_ENTRY_BOOL("dma-can-stall"), > + {}, > + }; > + > + if ((pdev->revision != 0x21) && (pdev->revision != 0x30)) > + return; > + > + pdev->eetlp_prefix_path = 1; > + > + /* Device-tree can set the stall property */ > + if (!pdev->dev.of_node && > + device_add_properties(&pdev->dev, properties)) Does this mean "dma-can-stall" *can* be set via DT, and if it is, this quirk is not needed? So is this quirk basically a workaround for an old or broken DT? > + pci_warn(pdev, "could not add stall property"); > +} > + Remove this blank line to follow the style of the rest of the file. > +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); > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0xa255, quirk_huawei_pcie_sva); > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0xa256, quirk_huawei_pcie_sva); > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0xa258, quirk_huawei_pcie_sva); > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0xa259, quirk_huawei_pcie_sva); > + > /* > * It's possible for the MSI to get corrupted if SHPC and ACPI are used > * together on certain PXH-based systems. > -- > 2.7.4 >
