diff options
| author | Dan Williams <dan.j.williams@intel.com> | 2014-05-20 18:08:40 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-05-27 16:38:52 -0700 |
| commit | 3bfd659baec822f54e4acb0734669e671d853a35 (patch) | |
| tree | c44ad6218e8b028e5595dd80e9c29213a8e96298 /drivers/usb/core/usb.h | |
| parent | 8b1ba80c59fb3e77f9e1761480617d5ea9ee159c (diff) | |
usb: find internal hub tier mismatch via acpi
ACPI identifies peer ports by setting their 'group_token' and
'group_position' _PLD data to the same value. If a platform has tier
mismatch [1] , ACPI can override the default (USB3 defined) peer port
association for internal hubs. External hubs follow the default peer
association scheme.
Location data is cached as an opaque cookie in usb_port_location data.
Note that we only consider the group_token and group_position attributes
from the _PLD data as ACPI specifies that group_token is a unique
identifier.
When we find port location data for a port then we assume that the
firmware will also describe its peer port. This allows the
implementation to only ever set the peer once. This leads to a question
about what happens when a pm runtime event occurs while the peer
associations are still resolving. Since we only ever set the peer
information once, a USB3 port needs to be prevented from suspending
while its ->peer pointer is NULL (implemented in a subsequent patch).
There is always the possibility that firmware mis-identifies the ports,
but there is not much the kernel can do in that case.
[1]: xhci 1.1 appendix D figure 131
[2]: acpi 5 section 6.1.8
[alan]: don't do default peering when acpi data present
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core/usb.h')
| -rw-r--r-- | drivers/usb/core/usb.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h index 6afa738b5ba4..98dc08e13448 100644 --- a/drivers/usb/core/usb.h +++ b/drivers/usb/core/usb.h @@ -171,6 +171,12 @@ extern void usbfs_conn_disc_event(void); extern int usb_devio_init(void); extern void usb_devio_cleanup(void); +/* + * Firmware specific cookie identifying a port's location. '0' == no location + * data available + */ +typedef u32 usb_port_location_t; + /* internal notify stuff */ extern void usb_notify_add_device(struct usb_device *udev); extern void usb_notify_remove_device(struct usb_device *udev); |