[PATCH RFC v4 2/9] powerpc/powernv/pci: Suppress an EEH error when reading an empty slot

[Oliver]

On Sat, Mar 2, 2019 at 3:04 AM Sergey Miroshnichenko
<s.miroshnichenko at yadro.com> wrote:
>
> Reading an empty slot returns all ones, which triggers a false
> EEH error event on PowerNV. This patch unfreezes the bus where
> it has happened.
>
> Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko at yadro.com>
> ---
>  arch/powerpc/include/asm/ppc-pci.h   |  1 +
>  arch/powerpc/kernel/pci_dn.c         |  2 +-
>  arch/powerpc/platforms/powernv/pci.c | 34 ++++++++++++++++++++++++----
>  3 files changed, 32 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/ppc-pci.h b/arch/powerpc/include/asm/ppc-pci.h
> index f67da277d652..737393c54f58 100644
> --- a/arch/powerpc/include/asm/ppc-pci.h
> +++ b/arch/powerpc/include/asm/ppc-pci.h
> @@ -40,6 +40,7 @@ void *traverse_pci_dn(struct pci_dn *root,
>                       void *(*fn)(struct pci_dn *, void *),
>                       void *data);
>  extern void pci_devs_phb_init_dynamic(struct pci_controller *phb);
> +struct pci_dn *pci_bus_to_pdn(struct pci_bus *bus);
>
>  /* From rtas_pci.h */
>  extern void init_pci_config_tokens (void);
> diff --git a/arch/powerpc/kernel/pci_dn.c b/arch/powerpc/kernel/pci_dn.c
> index ab147a1909c8..341ed71250f1 100644
> --- a/arch/powerpc/kernel/pci_dn.c
> +++ b/arch/powerpc/kernel/pci_dn.c
> @@ -40,7 +40,7 @@
>   * one of PF's bridge. For other devices, their firmware
>   * data is linked to that of their bridge.
>   */
> -static struct pci_dn *pci_bus_to_pdn(struct pci_bus *bus)
> +struct pci_dn *pci_bus_to_pdn(struct pci_bus *bus)
>  {
>         struct pci_bus *pbus;
>         struct device_node *dn;
> diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
> index 3260250d2029..73c2d0aed996 100644
> --- a/arch/powerpc/platforms/powernv/pci.c
> +++ b/arch/powerpc/platforms/powernv/pci.c
> @@ -761,6 +761,21 @@ static inline pnv_pci_cfg_check(struct pci_dn *pdn)
>  }
>  #endif /* CONFIG_EEH */
>
> +static int get_bus_pe_number(struct pci_bus *bus)
> +{
> +       struct pci_dn *pdn = pci_bus_to_pdn(bus);
> +       struct pci_dn *child;
> +
> +       if (!pdn)
> +               return IODA_INVALID_PE;
> +
> +       list_for_each_entry(child, &pdn->child_list, list)
> +               if (child->pe_number != IODA_INVALID_PE)
> +                       return child->pe_number;
> +
> +       return IODA_INVALID_PE;
> +}
> +
>  static int pnv_pci_read_config(struct pci_bus *bus,
>                                unsigned int devfn,
>                                int where, int size, u32 *val)
> @@ -769,12 +784,23 @@ static int pnv_pci_read_config(struct pci_bus *bus,
>         struct pci_controller *hose = pci_bus_to_host(bus);
>         struct pnv_phb *phb = hose->private_data;
>         int ret;
> +       u32 empty_val = 0xFFFFFFFF;
>
> -       *val = 0xFFFFFFFF;
> +       *val = empty_val;
>         pdn = pci_get_pdn_by_devfn(bus, devfn);
> -       if (!pdn)
> -               return pnv_pci_cfg_read_raw(phb->opal_id, bus->number, devfn,
> -                                           where, size, val);
> +       if (!pdn) {
> +               int pe_number = get_bus_pe_number(bus);
> +
> +               ret = pnv_pci_cfg_read_raw(phb->opal_id, bus->number, devfn,
> +                                          where, size, val);
> +
> +               if (!ret && (*val == empty_val) && phb->unfreeze_pe)

Do this empty val check work when using 1 or 2 byte cfg accesses?

> +                       phb->unfreeze_pe(phb, (pe_number == IODA_INVALID_PE) ?
> +                                        0xff : pe_number,

Use phb->ioda.reserved_pe_idx rather than guessing that 0xff is safe
to use. On P9 we have PHBs with 512 PEs and some older P8 firmware
releases used 0 as the reserved PE rather than 0xff.

> +                                        OPAL_EEH_ACTION_CLEAR_FREEZE_ALL);
> +
> +               return ret;
> +       }
>
>         if (!pnv_pci_cfg_check(pdn))
>                 return PCIBIOS_DEVICE_NOT_FOUND;
> --
> 2.20.1
>