Re: [PATCH 7/10] PCI / Hot-plug: Query _OSC before requesting controls

[Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>]

(2010/08/06 10:11), Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
> 
> It generally is unsafe to call acpi_pci_osc_control_set() without
> checking what _OSC bits the BIOS is willing to grant control of,
> because control of some _OSC bits may be granted even if
> acpi_pci_osc_control_set() returns AE_SUPPORT.  Therefore make
> acpi_get_hp_hw_control_from_firmware() use
> acpi_pci_osc_control_query() to check if the BIOS will grant
> OSC_SHPC_NATIVE_HP_CONTROL before calling acpi_pci_osc_control_set().
> 
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> ---
>  drivers/pci/hotplug/acpi_pcihp.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> Index: linux-2.6/drivers/pci/hotplug/acpi_pcihp.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/hotplug/acpi_pcihp.c
> +++ linux-2.6/drivers/pci/hotplug/acpi_pcihp.c
> @@ -358,11 +358,13 @@ int acpi_get_hp_hw_control_from_firmware
>  		acpi_get_name(handle, ACPI_FULL_PATHNAME, &string);
>  		dbg("Trying to get hotplug control for %s\n",
>  				(char *)string.pointer);
> +		status = acpi_pci_osc_control_query(handle, &flags);
> +		if (ACPI_FAILURE(status)
> +		    || !(flags & OSC_SHPC_NATIVE_HP_CONTROL))
> +			goto no_control;
>  		status = acpi_pci_osc_control_set(handle, flags);
>  		if (ACPI_SUCCESS(status))
>  			goto got_one;
> -		if (status == AE_SUPPORT)
> -			goto no_control;
>  		kfree(string.pointer);
>  		string = (struct acpi_buffer){ ACPI_ALLOCATE_BUFFER, NULL };
>  	}

This breaks fallback mechanism for OSHP, doesn't it?


Thanks.
H.Seto