On Mon, Feb 03, 2020 at 07:35:18PM +1100, Oliver O'Halloran wrote: > The pci hotplug helper (pci_hp_add_devices()) calls > eeh_add_device_tree_early() to scan the device-tree for new PCI devices and > do the early EEH probe before the device is scanned. This early probe is a > no-op in a lot of cases because: > > a) The early init is only required to satisfy a PAPR requirement that EEH > be configured before we start doing config accesses. On PowerNV it is > a no-op. > > b) It's a no-op for devices that have already had their eeh_dev > initialised. > > There are four callers of pci_hp_add_devices(): > > 1. arch/powerpc/kernel/eeh_driver.c > Here the hotplug helper is called when re-scanning pci_devs that > were removed during an EEH recovery pass. The EEH stat for each > removed device (the eeh_dev) is retained across a recovery pass > so the early init is a no-op in this case. > > 2. drivers/pci/hotplug/pnv_php.c > This is also a no-op since the PowerNV hotplug driver is, suprisingly, > PowerNV specific. > > 3. drivers/pci/hotplug/rpaphp_core.c > 4. drivers/pci/hotplug/rpaphp_pci.c > In these two cases new devices have been hotplugged and FW has > provided new DT nodes for each. These are the only two cases where > the EEH we might have new PCI device nodes in the DT so these are > the only two cases where the early EEH probe needs to be done. > > We can move the calls to eeh_add_device_tree_early() to the locations where > it's needed and remove it from the generic path. This is preparation for > making the early EEH probe pseries specific. > > Signed-off-by: Oliver O'Halloran <ooh...@gmail.com>
Makes sense to me.
Reviewed-by: Sam Bobroff <sbobr...@linux.ibm.com>
> ---
> arch/powerpc/kernel/pci-hotplug.c | 2 --
> drivers/pci/hotplug/rpaphp_core.c | 2 ++
> drivers/pci/hotplug/rpaphp_pci.c | 4 +++-
> 3 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/kernel/pci-hotplug.c
> b/arch/powerpc/kernel/pci-hotplug.c
> index d6a67f8..bf83f76 100644
> --- a/arch/powerpc/kernel/pci-hotplug.c
> +++ b/arch/powerpc/kernel/pci-hotplug.c
> @@ -112,8 +112,6 @@ void pci_hp_add_devices(struct pci_bus *bus)
> struct pci_controller *phb;
> struct device_node *dn = pci_bus_to_OF_node(bus);
>
> - eeh_add_device_tree_early(PCI_DN(dn));
> -
> phb = pci_bus_to_host(bus);
>
> mode = PCI_PROBE_NORMAL;
> diff --git a/drivers/pci/hotplug/rpaphp_core.c
> b/drivers/pci/hotplug/rpaphp_core.c
> index e408e40..9c1e43e 100644
> --- a/drivers/pci/hotplug/rpaphp_core.c
> +++ b/drivers/pci/hotplug/rpaphp_core.c
> @@ -494,6 +494,8 @@ static int enable_slot(struct hotplug_slot *hotplug_slot)
> return retval;
>
> if (state == PRESENT) {
> + eeh_add_device_tree_early(PCI_DN(slot->dn));
> +
> pci_lock_rescan_remove();
> pci_hp_add_devices(slot->bus);
> pci_unlock_rescan_remove();
> diff --git a/drivers/pci/hotplug/rpaphp_pci.c
> b/drivers/pci/hotplug/rpaphp_pci.c
> index beca61b..61ebbd8 100644
> --- a/drivers/pci/hotplug/rpaphp_pci.c
> +++ b/drivers/pci/hotplug/rpaphp_pci.c
> @@ -95,8 +95,10 @@ int rpaphp_enable_slot(struct slot *slot)
> return -EINVAL;
> }
>
> - if (list_empty(&bus->devices))
> + if (list_empty(&bus->devices)) {
> + eeh_add_device_tree_early(PCI_DN(slot->dn));
> pci_hp_add_devices(bus);
> + }
>
> if (!list_empty(&bus->devices)) {
> slot->state = CONFIGURED;
> --
> 2.9.5
>
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