| From 2dc3753997f3c80ce8b950242ab9bb3fb936acfd Mon Sep 17 00:00:00 2001 |
| From: Sarah Sharp <sarah.a.sharp@linux.intel.com> |
| Date: Fri, 2 Sep 2011 11:05:40 -0700 |
| Subject: xhci: If no endpoints changed, don't issue BW command. |
| |
| From: Sarah Sharp <sarah.a.sharp@linux.intel.com> |
| |
| commit 2dc3753997f3c80ce8b950242ab9bb3fb936acfd upstream. |
| |
| Some alternate interface settings have no endpoints associated with them. |
| This shows up in some USB webcams, particularly the Logitech HD 1080p, |
| which uses the uvcvideo driver. If a driver switches between two alt |
| settings with no endpoints, there is no need to issue a configure endpoint |
| command, because there is no endpoint information to update. |
| |
| The only time a configure endpoint command with just the add slot flag set |
| makes sense is when the driver is updating hub characteristics in the slot |
| context. However, that code never calls xhci_check_bandwidth, so we |
| should be safe not issuing a command if only the slot context add flag is |
| set. |
| |
| Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| drivers/usb/host/xhci.c | 6 ++++++ |
| 1 file changed, 6 insertions(+) |
| |
| --- a/drivers/usb/host/xhci.c |
| +++ b/drivers/usb/host/xhci.c |
| @@ -1888,6 +1888,12 @@ int xhci_check_bandwidth(struct usb_hcd |
| ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG); |
| ctrl_ctx->add_flags &= cpu_to_le32(~EP0_FLAG); |
| ctrl_ctx->drop_flags &= cpu_to_le32(~(SLOT_FLAG | EP0_FLAG)); |
| + |
| + /* Don't issue the command if there's no endpoints to update. */ |
| + if (ctrl_ctx->add_flags == cpu_to_le32(SLOT_FLAG) && |
| + ctrl_ctx->drop_flags == 0) |
| + return 0; |
| + |
| xhci_dbg(xhci, "New Input Control Context:\n"); |
| slot_ctx = xhci_get_slot_ctx(xhci, virt_dev->in_ctx); |
| xhci_dbg_ctx(xhci, virt_dev->in_ctx, |
