-----Original Message-----
From: Will Deacon [mailto:will.deacon at arm.com]
Sent: Friday, October 13, 2017 8:22 PM
To: Shameerali Kolothum Thodi <redacted>
Cc: lorenzo.pieralisi at arm.com; marc.zyngier at arm.com;
sudeep.holla at arm.com; robin.murphy at arm.com; joro at 8bytes.org;
bhelgaas at google.com; Gabriele Paoloni [off-list ref];
John Garry [off-list ref]; iommu at lists.linux-foundation.org;
linux-arm-kernel at lists.infradead.org; linux-acpi at vger.kernel.org; linux-
pci at vger.kernel.org; devel at acpica.org; Linuxarm [off-list ref];
Wangzhou (B) [off-list ref]; Guohanjun (Hanjun Guo)
[off-list ref]
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:

quoted

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

[off-list ref]

quoted

---
 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)

quoted

 	struct resource *reg;
 	int ret;

+	if ((IS_BUILTIN(CONFIG_ARM_SMMU_V3)) &&
+			of_property_read_bool(dev->of_node, "iommu-

map")) {

quoted

+		dev_warn(dev, "HiSilicon erratum 161010801: blacklisting

PCIe controllers behind SMMUv3\n");

quoted

+		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)

quoted

 	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")) {

quoted

+		dev_warn(dev, "HiSilicon erratum 161010801: blacklisting

PCIe controllers behind SMMUv3\n");

quoted

+		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.

Thanks,
Shameer

1. http://elixir.free-electrons.com/linux/v4.14-rc4/source/arch/arm64/boot/dts/hisilicon/hip07.dtsi
2. http://elixir.free-electrons.com/linux/v4.14-rc4/source/arch/arm64/boot/dts/hisilicon/hip06.dtsi