[-cc David, his email bounced]
On Wed, May 30, 2018 at 03:23:43PM -0500, Bjorn Helgaas wrote:
> [+cc David]
>
> On Mon, May 28, 2018 at 03:47:51PM +0300, Mika Westerberg wrote:
> > In the same way we do for pciehp, introduce a new function
> > shpchp_is_native() that returns true whether the bridge should be
> > handled by the native SHCP driver. Then convert the driver to use this
> > function.
> >
> > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> > ---
> > drivers/pci/hotplug/acpi_pcihp.c | 4 ++--
> > drivers/pci/hotplug/shpchp_core.c | 2 --
> > drivers/pci/pci-acpi.c | 21 +++++++++++++++++++++
> > include/linux/pci_hotplug.h | 2 ++
> > 4 files changed, 25 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/pci/hotplug/acpi_pcihp.c b/drivers/pci/hotplug/acpi_pcihp.c
> > index 597d22aeefc1..3979f89b250a 100644
> > --- a/drivers/pci/hotplug/acpi_pcihp.c
> > +++ b/drivers/pci/hotplug/acpi_pcihp.c
> > @@ -83,11 +83,11 @@ int acpi_get_hp_hw_control_from_firmware(struct pci_dev *pdev)
> > * OSHP within the scope of the hotplug controller and its parents,
> > * up to the host bridge under which this controller exists.
> > */
> > - host = pci_find_host_bridge(pdev->bus);
> > - if (host->native_shpc_hotplug)
> > + if (shpchp_is_native(pdev))
> > return 0;
> >
> > /* If _OSC exists, we should not evaluate OSHP */
> > + host = pci_find_host_bridge(pdev->bus);
> > root = acpi_pci_find_root(ACPI_HANDLE(&host->dev));
> > if (root->osc_support_set)
> > goto no_control;
> > diff --git a/drivers/pci/hotplug/shpchp_core.c b/drivers/pci/hotplug/shpchp_core.c
> > index 47decc9b3bb3..0f3711404c2b 100644
> > --- a/drivers/pci/hotplug/shpchp_core.c
> > +++ b/drivers/pci/hotplug/shpchp_core.c
> > @@ -275,8 +275,6 @@ static int is_shpc_capable(struct pci_dev *dev)
> > if (dev->vendor == PCI_VENDOR_ID_AMD &&
> > dev->device == PCI_DEVICE_ID_AMD_GOLAM_7450)
> > return 1;
> > - if (!pci_find_capability(dev, PCI_CAP_ID_SHPC))
> > - return 0;
> > if (acpi_get_hp_hw_control_from_firmware(dev))
> > return 0;
> > return 1;
> > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> > index 52b8434d4d6e..bb83be0d0e5b 100644
> > --- a/drivers/pci/pci-acpi.c
> > +++ b/drivers/pci/pci-acpi.c
> > @@ -394,6 +394,27 @@ bool pciehp_is_native(struct pci_dev *bridge)
> > return host->native_pcie_hotplug;
> > }
> >
> > +/**
> > + * shpchp_is_native - Check whether a hotplug port is handled by the OS
> > + * @bridge: Hotplug port to check
> > + *
> > + * Returns true if the given @bridge is handled by the native SHPC hotplug
> > + * driver.
> > + */
> > +bool shpchp_is_native(struct pci_dev *bridge)
> > +{
> > + const struct pci_host_bridge *host;
> > +
> > + if (!IS_ENABLED(CONFIG_HOTPLUG_PCI_SHPC))
> > + return false;
> > +
> > + if (!pci_find_capability(bridge, PCI_CAP_ID_SHPC))
> > + return false;
> > +
> > + host = pci_find_host_bridge(bridge->bus);
> > + return host->native_shpc_hotplug;
> > +}
>
> This is sort-of-but-not-exactly the same as is_shpc_capable().
>
> For PCI_DEVICE_ID_AMD_GOLAM_7450, is_shpc_capable() will return true
> and shpchp will claim the device, but shpchp_is_native() will return
> false because there's no SHPC capability.
>
> At least that's my interpretation of the AMD GOLAM stuff. I don't
> have a spec for it, but if GOLAM did have an SHPC capability, I assume
> is_shpc_capable() would look for it *before* testing for GOLAM.
>
> So I think these two things need to be reconciled somehow. I
> mentioned this before, but it was buried at the bottom of a long
> email, sorry about that.
>
> I wish we had a spec or details about the erratum. It looks like
> it's been there "forever": https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/drivers/pci/hotplug/shpchp.h?id=c16b4b14d9806e639f4afefa2d651a857a212afe
>
> But neither GOLAM (0x7450) nor POGO (0x7458) is in the PCI database at
> https://pci-ids.ucw.cz/read/PC/1002, so who knows if those chips ever
> even saw the light of day. I'll cc the author of
>
> 53044f357448 ("[PATCH] PCI Hotplug: shpchp: AMD POGO errata fix")
>
> But that was 12 years ago, so the email address may not even work any
> more.
>
> > /**
> > * pci_acpi_wake_bus - Root bus wakeup notification fork function.
> > * @context: Device wakeup context.
> > diff --git a/include/linux/pci_hotplug.h b/include/linux/pci_hotplug.h
> > index 1f5c935eb0de..4c378368215c 100644
> > --- a/include/linux/pci_hotplug.h
> > +++ b/include/linux/pci_hotplug.h
> > @@ -164,6 +164,7 @@ struct hotplug_params {
> > int pci_get_hp_params(struct pci_dev *dev, struct hotplug_params *hpp);
> > bool pciehp_is_native(struct pci_dev *bridge);
> > int acpi_get_hp_hw_control_from_firmware(struct pci_dev *bridge);
> > +bool shpchp_is_native(struct pci_dev *bridge);
> > int acpi_pci_check_ejectable(struct pci_bus *pbus, acpi_handle handle);
> > int acpi_pci_detect_ejectable(acpi_handle handle);
> > #else
> > @@ -178,5 +179,6 @@ static inline int acpi_get_hp_hw_control_from_firmware(struct pci_dev *bridge)
> > return 0;
> > }
> > static inline bool pciehp_is_native(struct pci_dev *bridge) { return true; }
> > +static inline bool shpchp_is_native(struct pci_dev *bridge) { return true; }
> > #endif
> > #endif
> > --
> > 2.17.0
> >
> --
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