On Fri, 2014-02-28 at 15:18 -0800, Dan Williams wrote:
> Given that root hub port peers are already established, external hub peer
> ports can be determined by traversing the device topology:
>
> 1/ ascend to the parent hub and find the upstream port_dev
>
> 2/ walk ->peer to find the peer port
>
> 3/ descend to the peer hub via ->child
>
> 4/ find the port with the matching port id
>
> Note that this assumes the port labeling scheme required by the
> specification [1].
>
> The usb_port_peer_mutex is held when marking hubs as disconnected
> (meaning all child ports are invalid for peering) and when the ->child
> pointer on a port_dev is marked NULL. Strictly speaking it seems the
> latter should be sufficient for protecting collisions with port peering.
> However, this still includes the lock around setting hub->disconnected
> for extra protection and documentation of the window for when a peer
> relationship can be established.
>
> [1]: usb3 3.1 section 10.3.3
>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Deleted the usb_port_peer_mutex usages added by this patch. They're
moot now given the locking done at the hub level.
8<---------
Subject: usb: assign usb3 external hub port peers
From: Dan Williams <dan.j.williams@xxxxxxxxx>
Given that root hub port peers are already established, external hub peer
ports can be determined by traversing the device topology:
1/ ascend to the parent hub and find the upstream port_dev
2/ walk ->peer to find the peer port
3/ descend to the peer hub via ->child
4/ find the port with the matching port id
Note that this assumes the port labeling scheme required by the
specification [1].
[1]: usb3 3.1 section 10.3.3
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/usb/core/port.c | 28 ++++++++++++++++++++--------
1 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index cb42352b97e6..6fd827e6a9f8 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -152,17 +152,17 @@ static struct device_driver usb_port_driver = {
};
/*
- * Set the default peer port for root hubs. Assumes the primary_hcd is
+ * Set the default peer port via the peer hcd for root hubs and the
+ * upstream peer relationship for other hubs. Assumes the primary_hcd is
* registered first
*/
static struct usb_port *find_default_peer(struct usb_hub *hub, int port1)
{
struct usb_device *hdev = hub->hdev;
- struct usb_port *peer = NULL;
+ struct usb_device *peer_hdev = NULL;
+ struct usb_hub *peer_hub;
if (!hdev->parent) {
- struct usb_hub *peer_hub;
- struct usb_device *peer_hdev;
struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
struct usb_hcd *peer_hcd = hcd->primary_hcd;
@@ -170,14 +170,26 @@ static struct usb_port *find_default_peer(struct usb_hub *hub, int port1)
return NULL;
peer_hdev = peer_hcd->self.root_hub;
- peer_hub = usb_hub_to_struct_hub(peer_hdev);
- if (!peer_hub || port1 > peer_hdev->maxchild)
+ } else {
+ struct usb_port *upstream;
+ struct usb_device *parent = hdev->parent;
+ struct usb_hub *parent_hub = usb_hub_to_struct_hub(parent);
+
+ if (!parent_hub)
+ return NULL;
+
+ upstream = parent_hub->ports[hdev->portnum - 1];
+ if (!upstream || !upstream->peer)
return NULL;
- peer = peer_hub->ports[port1 - 1];
+ peer_hdev = upstream->peer->child;
}
- return peer;
+ peer_hub = usb_hub_to_struct_hub(peer_hdev);
+ if (!peer_hub || port1 > peer_hdev->maxchild)
+ return NULL;
+
+ return peer_hub->ports[port1 - 1];
}
static void link_peers(struct usb_port *left, struct usb_port *right)
--
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