Re: [PATCH v2] ACPI:add _STA evaluating at do_acpi_find_child()

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Tuesday, May 28, 2013 11:22:17 AM jeff.wu@amd.com wrote:
> From: Jeff Wu <zlinuxkernel@gmail.com>
> 
> v2:
> 1).If it's only one matching device, whether the deivce status is enabled or disabled,
>    do_acpi_find_child() return its' handle
> 2).If it's more than one matching devices, do_acpi_find_child() return the first 
>    enabled device handle
> The idea mail thread:
> http://wwww.spinics.net/lists/linux-acpi/msg43481.html

The information what's changed in v2 with respect to v1 is rather not
interesting to the future readers of the changelog, so can you please rearrange
it as one comprehensive description of the patch?

The patch itself looks good to me.

Thanks,
Rafael


> v1:
> Once do_acpi_find_child() found the first matching handle, it makes the acpi_get_child()
> loop stop and return the matching handle. But, at some of the platforms, a "_ADR" is
> with the multiple devices, and if one is enabled, the others will be disabled.
> Just like a case:
> Address : 0x1FFFF ; handle : SB_PCI0.SATA.DEV0
> Address : 0x1FFFF ; handle : SB_PCI0.SATA.DEV1
> Address : 0x1FFFF ; handle : SB_PCI0.SATA.DEV2
> 
> If DEV0 and DEV1 are disabled and DEV2 is enabled, the target is to get DEV2 handle, but
> actually it always return the first disabled device DEV0 handle. So add a _STA evaluating
> at do_acpi_find_child() to check the device status. If the object exists, but it is disabled,
> acpi_get_child() will continue looping to get the correct handle that the object exists and
> is enabled.
>  
> 
> Signed-off-by: Jeff Wu <zlinuxkernel@gmail.com>
> ---
>  drivers/acpi/glue.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
> index 40a84cc..51ca764 100644
> --- a/drivers/acpi/glue.c
> +++ b/drivers/acpi/glue.c
> @@ -81,13 +81,15 @@ static struct acpi_bus_type *acpi_get_bus_type(struct device *dev)
>  static acpi_status do_acpi_find_child(acpi_handle handle, u32 lvl_not_used,
>  				      void *addr_p, void **ret_p)
>  {
> -	unsigned long long addr;
> +	unsigned long long addr, sta;
>  	acpi_status status;
>  
>  	status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, &addr);
>  	if (ACPI_SUCCESS(status) && addr == *((u64 *)addr_p)) {
>  		*ret_p = handle;
> -		return AE_CTRL_TERMINATE;
> +		status = acpi_bus_get_status_handle(handle, &sta);
> +		if (ACPI_SUCCESS(status) && (sta & ACPI_STA_DEVICE_ENABLED))
> +			return AE_CTRL_TERMINATE;
>  	}
>  	return AE_OK;
>  }
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.