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USB: usblp: don't call usb_set_interface if there's a single alt

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commit d8c6edfa3f upstream.

Some devices, such as the Winbond Electronics Corp. Virtual Com Port
(Vendor=0416, ProdId=5011), lockup when usb_set_interface() or
usb_clear_halt() are called. This device has only a single
altsetting, so it should not be necessary to call usb_set_interface().

Acked-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Jeremy Figgins <kernel@jeremyfiggins.com>
Link: https://lore.kernel.org/r/YAy9kJhM/rG8EQXC@watson
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jeremy Figgins
2021-01-23 18:21:36 -06:00
committed by Chris
parent 926fa605b7
commit f9acef863a
1 changed files with 11 additions and 8 deletions
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19
drivers/usb/class/usblp.c
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@@ -1349,14 +1349,17 @@ static int usblp_set_protocol(struct usblp *usblp, int protocol)
if (protocol < USBLP_FIRST_PROTOCOL || protocol > USBLP_LAST_PROTOCOL)
return -EINVAL;
alts = usblp->protocol[protocol].alt_setting;
if (alts < 0)
return -EINVAL;
r = usb_set_interface(usblp->dev, usblp->ifnum, alts);
if (r < 0) {
printk(KERN_ERR "usblp: can't set desired altsetting %d on interface %d\n",
alts, usblp->ifnum);
return r;
/* Don't unnecessarily set the interface if there's a single alt. */
if (usblp->intf->num_altsetting > 1) {
alts = usblp->protocol[protocol].alt_setting;
if (alts < 0)
return -EINVAL;
r = usb_set_interface(usblp->dev, usblp->ifnum, alts);
if (r < 0) {
printk(KERN_ERR "usblp: can't set desired altsetting %d on interface %d\n",
alts, usblp->ifnum);
return r;
}
}
usblp->bidir = (usblp->protocol[protocol].epread != NULL);