Hi Sergey, On Thu, Sep 06, 2018 at 02:57:52PM +0300, Sergey Miroshnichenko wrote: > Reading an empty slot returns all ones, which triggers a false > EEH error event on PowerNV. > > New callbacks pcibios_rescan_prepare/done are introduced to > pause/resume the EEH during rescan.
If I understand it correctly, this temporarily disables EEH for config space
accesses on the whole PHB while the rescan runs. Is it possible that a
real EEH event could be missed if it occurred during the rescan?
Even if it's not possible, I think it would be good to mention that in a
comment.
> Signed-off-by: Sergey Miroshnichenko <s.miroshniche...@yadro.com>
> ---
> arch/powerpc/include/asm/eeh.h | 2 ++
> arch/powerpc/kernel/eeh.c | 12 +++++++++++
> arch/powerpc/platforms/powernv/eeh-powernv.c | 22 ++++++++++++++++++++
> drivers/pci/probe.c | 14 +++++++++++++
> include/linux/pci.h | 2 ++
> 5 files changed, 52 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/eeh.h b/arch/powerpc/include/asm/eeh.h
> index 219637ea69a1..926c3e31df99 100644
> --- a/arch/powerpc/include/asm/eeh.h
> +++ b/arch/powerpc/include/asm/eeh.h
> @@ -219,6 +219,8 @@ struct eeh_ops {
> int (*next_error)(struct eeh_pe **pe);
> int (*restore_config)(struct pci_dn *pdn);
> int (*notify_resume)(struct pci_dn *pdn);
> + int (*pause)(struct pci_bus *bus);
> + int (*resume)(struct pci_bus *bus);
I think these names are a bit too generic, what about naming them
pause_bus()/resume_bus() or even prepare_rescan()/rescan_done()?
> };
>
> extern int eeh_subsystem_flags;
> diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
> index 6ebba3e48b01..9fb5012f389d 100644
> --- a/arch/powerpc/kernel/eeh.c
> +++ b/arch/powerpc/kernel/eeh.c
> @@ -1831,3 +1831,15 @@ static int __init eeh_init_proc(void)
> return 0;
> }
> __initcall(eeh_init_proc);
> +
> +void pcibios_rescan_prepare(struct pci_bus *bus)
> +{
> + if (eeh_ops && eeh_ops->pause)
> + eeh_ops->pause(bus);
> +}
> +
> +void pcibios_rescan_done(struct pci_bus *bus)
> +{
> + if (eeh_ops && eeh_ops->resume)
> + eeh_ops->resume(bus);
> +}
> diff --git a/arch/powerpc/platforms/powernv/eeh-powernv.c
> b/arch/powerpc/platforms/powernv/eeh-powernv.c
> index 3c1beae29f2d..9724a58afcd2 100644
> --- a/arch/powerpc/platforms/powernv/eeh-powernv.c
> +++ b/arch/powerpc/platforms/powernv/eeh-powernv.c
> @@ -59,6 +59,26 @@ void pnv_pcibios_bus_add_device(struct pci_dev *pdev)
> eeh_sysfs_add_device(pdev);
> }
>
> +static int pnv_eeh_pause(struct pci_bus *bus)
> +{
> + struct pci_controller *hose = pci_bus_to_host(bus);
> + struct pnv_phb *phb = hose->private_data;
> +
> + phb->flags &= ~PNV_PHB_FLAG_EEH;
> + disable_irq(eeh_event_irq);
> + return 0;
> +}
> +
> +static int pnv_eeh_resume(struct pci_bus *bus)
> +{
> + struct pci_controller *hose = pci_bus_to_host(bus);
> + struct pnv_phb *phb = hose->private_data;
> +
> + enable_irq(eeh_event_irq);
> + phb->flags |= PNV_PHB_FLAG_EEH;
> + return 0;
> +}
> +
> static int pnv_eeh_init(void)
> {
> struct pci_controller *hose;
> @@ -1710,6 +1730,8 @@ static struct eeh_ops pnv_eeh_ops = {
> .write_config = pnv_eeh_write_config,
> .next_error = pnv_eeh_next_error,
> .restore_config = pnv_eeh_restore_config,
> + .pause = pnv_eeh_pause,
> + .resume = pnv_eeh_resume,
> .notify_resume = NULL
> };
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index ac876e32de4b..4a9045364809 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -2801,6 +2801,14 @@ void __weak pcibios_remove_bus(struct pci_bus *bus)
> {
> }
>
> +void __weak pcibios_rescan_prepare(struct pci_bus *bus)
> +{
> +}
> +
> +void __weak pcibios_rescan_done(struct pci_bus *bus)
> +{
> +}
> +
> struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
> struct pci_ops *ops, void *sysdata, struct list_head *resources)
> {
> @@ -3055,9 +3063,15 @@ unsigned int pci_rescan_bus_bridge_resize(struct
> pci_dev *bridge)
> unsigned int pci_rescan_bus(struct pci_bus *bus)
> {
> unsigned int max;
> + struct pci_bus *root = bus;
> +
> + while (!pci_is_root_bus(root))
> + root = root->parent;
>
> + pcibios_rescan_prepare(root);
> max = pci_scan_child_bus(bus);
> pci_assign_unassigned_bus_resources(bus);
> + pcibios_rescan_done(root);
> pci_bus_add_devices(bus);
>
> return max;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 340029b2fb38..42930731c5a7 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1929,6 +1929,8 @@ void pcibios_penalize_isa_irq(int irq, int active);
> int pcibios_alloc_irq(struct pci_dev *dev);
> void pcibios_free_irq(struct pci_dev *dev);
> resource_size_t pcibios_default_alignment(void);
> +void pcibios_rescan_prepare(struct pci_bus *bus);
> +void pcibios_rescan_done(struct pci_bus *bus);
>
> #ifdef CONFIG_HIBERNATE_CALLBACKS
> extern struct dev_pm_ops pcibios_pm_ops;
> --
> 2.17.1
>
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