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authorDan Williams <dan.j.williams@intel.com>2014-05-21 05:08:28 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-05-28 03:38:52 +0400
commitd8521afe35862f4fbe3ccd6ca37897c0a304edf3 (patch)
tree954c24e20f738a5b6fd0c7038bffdd5e8c71f211 /drivers/usb/core/usb.h
parenta4204ff0bd576fc114357eed70e7c4e776ddf396 (diff)
downloadlinux-d8521afe35862f4fbe3ccd6ca37897c0a304edf3.tar.xz
usb: assign default peer ports for root hubs
Assume that the peer of a superspeed port is the port with the same id on the shared_hcd root hub. This identification scheme is required of external hubs by the USB3 spec [1]. However, for root hubs, tier mismatch may be in effect [2]. Tier mismatch can only be enumerated via platform firmware. For now, simply perform the nominal association. A new lock 'usb_port_peer_mutex' is introduced to synchronize port device add/remove with peer lookups. It protects peering against changes to hcd->shared_hcd, hcd->self.root_hub, hdev->maxchild, and port_dev->child pointers. [1]: usb 3.1 section 10.3.3 [2]: xhci 1.1 appendix D Cc: Alan Stern <stern@rowland.harvard.edu> [alan: usb_port_peer_mutex locking scheme] 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.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h
index 69bfc253a7b8..6afa738b5ba4 100644
--- a/drivers/usb/core/usb.h
+++ b/drivers/usb/core/usb.h
@@ -119,6 +119,7 @@ static inline int usb_set_usb2_hardware_lpm(struct usb_device *udev, int enable)
#endif
extern struct bus_type usb_bus_type;
+extern struct mutex usb_port_peer_mutex;
extern struct device_type usb_device_type;
extern struct device_type usb_if_device_type;
extern struct device_type usb_ep_device_type;