Hi Tianyu,
I was talking to Alan Cox about the port power off mechanism, and he
suggested it might be good to expose the power resource information to
userspace via sysfs. Then the user could figure out which of their
devices are connected to which power resources. For example, users
could move devices that we can't safely power off to the same power
resource, instead of connecting them to several power resources.
Alan also suggested that the default for unconnectable USB ports should
be the "auto" setting instead of the "on" setting. His point was that
it's hard to add more aggressive power savings later on, and we should
just turn on the power savings and see if anyone complains. Then we'll
get more real user testing with systems that have ACPI tables from other
BIOS vendors, and we can see if the ACPI tables are sane.
Also, Bob Moore pointed out that we could use the _PLD ACPI method to
give users a better idea of the physical location of ports associated
with a power resource. I note that this patch adds support for the
physical device location data. Is that exposed to userspace via sysfs?
If not, maybe we should expose the _PLD values along with the "User
Visiable" and "Port is Connectable" ACPI values in the new port
directory.
Sarah Sharp
On Fri, May 04, 2012 at 11:06:37AM +0800, Lan Tianyu wrote:
> From: Matthew Garrett <mjg@xxxxxxxxxx>
>
> Add a simple helper function to allow drivers to obtain the physical
> device location data.
>
> Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
> ---
> drivers/acpi/utils.c | 29 +++++++++++++++++++++++++++++
> include/acpi/acpi_bus.h | 31 +++++++++++++++++++++++++++++++
> 2 files changed, 60 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
> index b002a47..5c320a0 100644
> --- a/drivers/acpi/utils.c
> +++ b/drivers/acpi/utils.c
> @@ -382,3 +382,32 @@ acpi_evaluate_reference(acpi_handle handle,
> }
>
> EXPORT_SYMBOL(acpi_evaluate_reference);
> +
> +acpi_status
> +acpi_get_physical_device_location(acpi_handle handle, struct acpi_pld *pld)
> +{
> + acpi_status status;
> + struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> + union acpi_object *output;
> +
> + status = acpi_evaluate_object(handle, "_PLD", NULL, &buffer);
> +
> + if (ACPI_FAILURE(status))
> + return status;
> +
> + output = buffer.pointer;
> +
> + if (!output || output->type != ACPI_TYPE_PACKAGE
> + || !output->package.count
> + || output->package.elements[0].type != ACPI_TYPE_BUFFER
> + || output->package.elements[0].buffer.length > sizeof(*pld)) {
> + status = AE_TYPE;
> + goto out;
> + }
> +
> + memcpy(pld, output->package.elements[0].buffer.pointer,
> + output->package.elements[0].buffer.length);
> +out:
> + kfree(buffer.pointer);
> + return status;
> +}
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index f1c8ca6..2642744 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -51,6 +51,37 @@ acpi_evaluate_reference(acpi_handle handle,
> struct acpi_object_list *arguments,
> struct acpi_handle_list *list);
>
> +struct acpi_pld {
> + unsigned int revision:7; /* 0 */
> + unsigned int ignore_colour:1; /* 7 */
> + unsigned int colour:24; /* 8 */
> + unsigned int width:16; /* 32 */
> + unsigned int height:16; /* 48 */
> + unsigned int user_visible:1; /* 64 */
> + unsigned int dock:1; /* 65 */
> + unsigned int lid:1; /* 66 */
> + unsigned int panel:3; /* 67 */
> + unsigned int vertical_pos:2; /* 70 */
> + unsigned int horizontal_pos:2; /* 72 */
> + unsigned int shape:4; /* 74 */
> + unsigned int group_orientation:1; /* 78 */
> + unsigned int group_token:8; /* 79 */
> + unsigned int group_position:8; /* 87 */
> + unsigned int bay:1; /* 95 */
> + unsigned int ejectable:1; /* 96 */
> + unsigned int ospm_eject_required:1; /* 97 */
> + unsigned int cabinet_number:8; /* 98 */
> + unsigned int card_cage_number:8; /* 106 */
> + unsigned int reference:1; /* 114 */
> + unsigned int rotation:4; /* 115 */
> + unsigned int order:5; /* 119 */
> + unsigned int reserved:4; /* 124 */
> + unsigned int vertical_offset:16; /* 128 */
> + unsigned int horizontal_offset:16; /* 144 */
> +};
> +
> +acpi_status
> +acpi_get_physical_device_location(acpi_handle handle, struct acpi_pld *pld);
> #ifdef CONFIG_ACPI
>
> #include <linux/proc_fs.h>
> --
> 1.7.6.rc2.8.g28eb
>
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