Re: [Qemu-devel] [BUG] -usb makes qemu fight against linux

[Paul Bolle <pebolle@tiscali.nl>]

On Fri, 2009-03-06 at 09:54 +0100, Stan Behrens wrote:
> when you add a bluetooth-dongle, usb-flash-drive or something like that via:
> usb_add host:2.23
> to you're guest-OS, qemu starts to fight against the linux-usb-configuration.
> 
> qemu's output looks like this:
> husb: open device 2.32
> husb: config #1 need -1
> husb: 1 interfaces claimed for configuration 1
> husb: grabbed usb device 2.32
> husb: config #1 need 1
> husb: 1 interfaces claimed for configuration 1
> husb: config #1 need 1
> husb: 1 interfaces claimed for configuration 1
> husb: config #1 need 1
> husb: 1 interfaces claimed for configuration 1
> husb: config #1 need 1
> husb: 1 interfaces claimed for configuration 1
> 
> And '# dmesg' says:
> [12929.001037] usb 2-3: reset high speed USB device using ehci_hcd and address 32
> [12929.782032] usb 2-3: reset high speed USB device using ehci_hcd and address 32
> [12930.176041] usb 2-3: reset high speed USB device using ehci_hcd and address 32
> [12930.726032] usb 2-3: reset high speed USB device using ehci_hcd and address 32

This seems related to this discussion:
http://lists.gnu.org/archive/html/qemu-devel/2008-10/msg01320.html (in a
thread regarding a preliminary patch to implement ehci).

Could you try the following patch? It was created after finally
discovering the discussion mentioned above (which I hardly understand,
which in turn leads to an impressive, but possibly nonsensical commit
message for this patch). It seems to fix a similar issue I ran into
(while trying some advanced feature of a USB memory stick I happen to
have.)


Paul Bolle
---
[PATCH] usb-linux: use USB_RET_STALL on -EPIPE URB status

If ioctl([...], USBDEVFS_REAPURBNDELAY, [...]) sets the URB status to
-EPIPE use USB_RET_STALL (and not USB_RET_NAK). USB_RET_NAK can confuse
guests and seems to trigger some guests to repeatedly request port
resets, which slows down (or even blocks) USB operations.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
---
 usb-linux.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/usb-linux.c b/usb-linux.c
index 70d7a1c..80ef6fc 100644
--- a/usb-linux.c
+++ b/usb-linux.c
@@ -277,7 +277,7 @@ static void async_complete(void *opaque)
                 set_halt(s, p->devep);
                 /* fall through */
             default:
-                p->len = USB_RET_NAK;
+                p->len = USB_RET_STALL;
                 break;
             }
 
-- 
1.6.2.2