On Sun, Oct 15, 2017 at 07:46:34AM +0000, Shameerali Kolothum Thodi wrote: > > > > -----Original Message----- > > From: Will Deacon [mailto:will.deacon@xxxxxxx] > > Sent: Friday, October 13, 2017 8:22 PM > > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> > > Cc: lorenzo.pieralisi@xxxxxxx; marc.zyngier@xxxxxxx; > > sudeep.holla@xxxxxxx; robin.murphy@xxxxxxx; joro@xxxxxxxxxx; > > bhelgaas@xxxxxxxxxx; Gabriele Paoloni <gabriele.paoloni@xxxxxxxxxx>; > > John Garry <john.garry@xxxxxxxxxx>; iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; > > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; linux- > > pci@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx; Linuxarm <linuxarm@xxxxxxxxxx>; > > Wangzhou (B) <wangzhou1@xxxxxxxxxxxxx>; Guohanjun (Hanjun Guo) > > <guohanjun@xxxxxxxxxx> > > Subject: Re: [PATCH v9 4/4] PCI: hisi: blacklist hip06/hip07 controllers behind > > SMMUv3 > > > > On Fri, Oct 06, 2017 at 03:04:50PM +0100, Shameer Kolothum wrote: > > > The HiSilicon erratum 161010801 describes the limitation of HiSilicon > > > platforms hip06/hip07 to support the SMMUv3 mappings for MSI > > > transactions. > > > > > > PCIe controller on these platforms has to differentiate the MSI > > > payload against other DMA payload and has to modify the MSI payload. > > > This basically makes it difficult for this platforms to have a SMMU > > > translation for MSI. In order to workaround this, ARM > > > SMMUv3 driver requires a quirk to treat the MSI regions separately. > > > Such a quirk is currently missing for DT based systems and therefore > > > we need to blacklist the hip06/hip07 PCIe controllers. > > > > > > Signed-off-by: Shameer Kolothum > > <shameerali.kolothum.thodi@xxxxxxxxxx> > > > --- > > > drivers/pci/dwc/pcie-hisi.c | 12 ++++++++++++ > > > 1 file changed, 12 insertions(+) > > > > > > diff --git a/drivers/pci/dwc/pcie-hisi.c b/drivers/pci/dwc/pcie-hisi.c > > > index a201791..6800747 100644 > > > --- a/drivers/pci/dwc/pcie-hisi.c > > > +++ b/drivers/pci/dwc/pcie-hisi.c > > > @@ -270,6 +270,12 @@ static int hisi_pcie_probe(struct platform_device > > *pdev) > > > struct resource *reg; > > > int ret; > > > > > > + if ((IS_BUILTIN(CONFIG_ARM_SMMU_V3)) && > > > + of_property_read_bool(dev->of_node, "iommu- > > map")) { > > > + dev_warn(dev, "HiSilicon erratum 161010801: blacklisting > > PCIe controllers behind SMMUv3\n"); > > > + return -ENODEV; > > > + } > > > + > > > hisi_pcie = devm_kzalloc(dev, sizeof(*hisi_pcie), GFP_KERNEL); > > > if (!hisi_pcie) > > > return -ENOMEM; > > > @@ -340,6 +346,12 @@ static int hisi_pcie_almost_ecam_probe(struct > > platform_device *pdev) > > > struct device *dev = &pdev->dev; > > > struct pci_ecam_ops *ops; > > > > > > + if ((IS_BUILTIN(CONFIG_ARM_SMMU_V3)) && > > > + of_property_read_bool(dev->of_node, "iommu- > > map")) { > > > + dev_warn(dev, "HiSilicon erratum 161010801: blacklisting > > PCIe controllers behind SMMUv3\n"); > > > + return -ENODEV; > > > + } > > > > This isn't the right way to solve this problem. I was really hoping you'd come > > up with a solution for DT, and I know you've been trying, so I suppose for > > now we'll just have to go with the ACPI workaround you have and leave DT in > > the balance. I'm not at all happy with that, but I don't think this patch really > > improves things. > > Yes Will, this is to get the ACPI support enabled for now. > > > What I think you should do is remove the relevant smmu/iommu-map > > entries from the .dts files that are available for these platforms (i.e. > > comment them out with a description as to why). > > We don't have any smmu/iommu-map entries for these platforms in the > .dts files [1][2]. We are not aiming for any official DT support for these platforms. > This patch is to enforce the non-support. Understood, but this has dragged on for a while and I don't think this patch is the right way to enforce things. The best approach might actually be to add the SMMU to the DTs, but commented out with a comment explaining why it's not a good idea to enable it. Will
