On Fri, Sep 23, 2022 at 01:37:57PM -0700, francisco.munoz.ruiz@xxxxxxxxxxxxxxx wrote:
> From: Francisco Munoz <francisco.munoz.ruiz@xxxxxxxxxxxxxxx>
>
> The reset was never applied in the current implementation because Intel
> Bridges owned by VMD are parentless. Internally, the reset API applies
> a reset to the parent of the pci device supplied as argument, but in this
> case it failed because there wasn't a parent. This change feeds a child
> device of an Intel Bridge to the reset API and internally the reset is
> applied to its parent.
What kind of problem does this fix? I guess some devices below a VMD
need to be reset before we can use them?
As a rule, Linux doesn't reset PCI devices at boot, so I'm just
wondering what's different about these.
If this fixes a problem, it's also nice if we can include a symptom in
the commit log so if people are seeing the problem, they can find the
solution, or distros can tell whether they need to include it.
> Signed-off-by: Francisco Munoz <francisco.munoz.ruiz@xxxxxxxxxxxxxxx>
> Reviewed-by: Nirmal Patel <nirmal.patel@xxxxxxxxxxxxxxx>
> ---
> drivers/pci/controller/vmd.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index e06e9f4fc50f..34d6ba675440 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -859,8 +859,16 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
>
> pci_scan_child_bus(vmd->bus);
> vmd_domain_reset(vmd);
> - list_for_each_entry(child, &vmd->bus->children, node)
> - pci_reset_bus(child->self);
> +
> + list_for_each_entry(child, &vmd->bus->children, node) {
> + if (!list_empty(&child->devices)) {
> + pci_reset_bus(list_first_entry(&child->devices,
> + struct pci_dev,
> + bus_list));
> + break;
> + }
> + }
> +
> pci_assign_unassigned_bus_resources(vmd->bus);
>
> /*
> --
> 2.25.1
>
