On 2020/6/10 下午3:46, Jean-Philippe Brucker wrote:
On Wed, Jun 10, 2020 at 12:18:14PM +0800, Zhangfei Gao wrote:
Some platform devices appear as PCI and have PCI cfg space,
but are actually on the AMBA bus.
They can support PASID via smmu stall feature, but does not
support tlp since they are not real pci devices.
So remove tlp as a PASID dependency.
Signed-off-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
---
drivers/pci/ats.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index 390e92f..8e31278 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -344,9 +344,6 @@ int pci_enable_pasid(struct pci_dev *pdev, int features)
if (WARN_ON(pdev->pasid_enabled))
return -EBUSY;
- if (!pdev->eetlp_prefix_path)
- return -EINVAL;
-
This check is useful, and follows the PCI specification (4.0r1.0
2.2.10.2 End-End TLP Prefix Processing: "Software should ensure that TLPs
containing End-End TLP Prefixes are not sent to components that do not
support them.")
Thanks Jean,
Why not set the eetlp_prefix_path bit from a PCI quirk? Unlike the stall
problem from the other thread, this one looks like a simple design mistake
that can be fixed easily in future iterations of the platform: just set
the "End-End TLP Prefix Supported" bit in the Device Capability 2 Register
of all bridges.
Yes, we can still set eetlp_prefix_path bit from a PCI quirk.
And we also have considered adding this bit in Device Capability 2
Register in future silicon.
But we hesitated that it does reflect the real function: from register,
it can support tlp, but in fact, it does not.
Thanks
