Previously we assumed that PCIe Root Ports and Downstream Ports had Links
on their secondary side. That is true in most systems, but it is possible
to connect a switch with either an Upstream or a Downstream Port leading
downstream.
Instead of relying on the component type to identify devices that have
links leading downstream, use the "dev->has_secondary_link" field.
[bhelgaas: changelog]
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
These are set of two capability registers, it's pretty much given that
they're registers, so reflect their purpose in the name.
Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
While we don't really have any infrastructure for making use of VC
support, the system BIOS can configure the topology to non-default
VC values prior to boot. This may be due to silicon bugs, desire to
reserve traffic classes, or perhaps just BIOS bugs. When we reset
devices, the VC configuration may return to default values, which can
be incompatible with devices upstream. For instance, Nvidia GRID
cards provide a PCIe switch and some number of GPUs, all supporting
VC. The power-on default for VC is to support TC0-7 across VC0,
however some platforms will only enable TC0/VC0 mapping across the
topology. When we do a secondary bus reset on the downstream switch
port, the GPU is reset to a TC0-7/VC0 mapping while the opposite end
of the link only enables TC0/VC0. If the GPU attempts to use TC1-7,
it fails.
This patch attempts to provide complete support for VC save/restore,
even beyond the minimally required use case above. This includes
save/restore and reload of the arbitration table, save/restore and
reload of the port arbitration tables, and re-enabling of the
channels for VC, VC9, and MFVC capabilities.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Yijing Wang
Alex Williamson