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SubjectRe: [PATCH 1/1] PCI: acpi_pcihp, run _OSC on a root bridge
* Jesse Barnes <jbarnes@virtuousgeek.org>:
> [Cc'ing Alex & Kenji-san for their comments on this fix.]
>
> On Monday, August 11, 2008 8:47 am Jiri Slaby wrote:
> > _OSC should be ran on a root bridge instead of the device itself.
> > Do this before touching OSHP since PCI fw specs states that _OSC
> > should be preferred over OSHP (however if the device has OSHP but
> > not _OSC -- not a root bridge -- it's not).

Reviewed the PCI fw spec (v3.0) and this code, and Jiri's change
seems sane to me.

One minor nit below.

> >
> > Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
> > Cc: kristen.c.accardi@intel.com
> > Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
> > ---
> > drivers/pci/hotplug/acpi_pcihp.c | 41
> > ++++++++++++++++++++++++++----------- 1 files changed, 29 insertions(+), 12
> > deletions(-)
> >
> > diff --git a/drivers/pci/hotplug/acpi_pcihp.c
> > b/drivers/pci/hotplug/acpi_pcihp.c index 93e37f0..bd83197 100644
> > --- a/drivers/pci/hotplug/acpi_pcihp.c
> > +++ b/drivers/pci/hotplug/acpi_pcihp.c
> > @@ -382,7 +382,7 @@ EXPORT_SYMBOL_GPL(acpi_get_hp_params_from_firmware);
> > int acpi_get_hp_hw_control_from_firmware(struct pci_dev *dev, u32 flags)
> > {
> > acpi_status status;
> > - acpi_handle chandle, handle = DEVICE_ACPI_HANDLE(&(dev->dev));
> > + acpi_handle chandle, handle;
> > struct pci_dev *pdev = dev;
> > struct pci_bus *parent;
> > struct acpi_buffer string = { ACPI_ALLOCATE_BUFFER, NULL };
> > @@ -399,10 +399,28 @@ int acpi_get_hp_hw_control_from_firmware(struct
> > pci_dev *dev, u32 flags) * Per PCI firmware specification, we should run
> > the ACPI _OSC
> > * method to get control of hotplug hardware before using it. If
> > * an _OSC is missing, we look for an OSHP to do the same thing.
> > - * To handle different BIOS behavior, we look for _OSC and OSHP
> > - * within the scope of the hotplug controller and its parents,
> > + * To handle different BIOS behavior, we look for _OSC on a root
> > + * bridge preferentially (according to PCI fw spec). Later for
> > + * OSHP within the scope of the hotplug controller and its parents,
> > * upto the host bridge under which this controller exists.
> > */
> > + while (pdev->bus->self)
> > + pdev = pdev->bus->self;
> > + handle = acpi_get_pci_rootbridge_handle(pci_domain_nr(pdev->bus),
> > + pdev->bus->number);

This looks an awful lot like the first few lines of
aer_osc_setup(). Any chance you could factor those lines out into
a common inline?

static inline acpi_handle acpi_find_root_bridge_handle(struct pci_dev *pdev)
{
while (pdev->bus->self)
pdev = pdev->bus->self;

return acpi_get_pci_rootbridge_handle(pci_domain_nr(pdev->bus),
pdev->bus->number);
}

<linux/pci-acpi.h> might be a good place for that.

Just a thought.

But otherwise,

Acked-by: Alex Chiang <achiang@hp.com>

Thanks.

/ac

> > + if (handle) {
> > + acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
> > + dbg("Trying to get hotplug control for %s\n",
> > + (char *)string.pointer);
> > + status = pci_osc_control_set(handle, flags);
> > + if (ACPI_SUCCESS(status))
> > + goto got_one;
> > + kfree(string.pointer);
> > + string = (struct acpi_buffer){ ACPI_ALLOCATE_BUFFER, NULL };
> > + }
> > +
> > + pdev = dev;
> > + handle = DEVICE_ACPI_HANDLE(&dev->dev);
> > while (!handle) {
> > /*
> > * This hotplug controller was not listed in the ACPI name
> > @@ -427,15 +445,9 @@ int acpi_get_hp_hw_control_from_firmware(struct
> > pci_dev *dev, u32 flags) acpi_get_name(handle, ACPI_FULL_PATHNAME,
> > &string);
> > dbg("Trying to get hotplug control for %s \n",
> > (char *)string.pointer);
> > - status = pci_osc_control_set(handle, flags);
> > - if (status == AE_NOT_FOUND)
> > - status = acpi_run_oshp(handle);
> > - if (ACPI_SUCCESS(status)) {
> > - dbg("Gained control for hotplug HW for pci %s (%s)\n",
> > - pci_name(dev), (char *)string.pointer);
> > - kfree(string.pointer);
> > - return 0;
> > - }
> > + status = acpi_run_oshp(handle);
> > + if (ACPI_SUCCESS(status))
> > + goto got_one;
> > if (acpi_root_bridge(handle))
> > break;
> > chandle = handle;
> > @@ -449,6 +461,11 @@ int acpi_get_hp_hw_control_from_firmware(struct
> > pci_dev *dev, u32 flags)
> >
> > kfree(string.pointer);
> > return -ENODEV;
> > +got_one:
> > + dbg("Gained control for hotplug HW for pci %s (%s)\n", pci_name(dev),
> > + (char *)string.pointer);
> > + kfree(string.pointer);
> > + return 0;
> > }
> > EXPORT_SYMBOL(acpi_get_hp_hw_control_from_firmware);
>
>
>
> --
> Jesse Barnes, Intel Open Source Technology Center
>


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