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

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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 <[email protected]>
Signed-off-by: Jeremy Figgins <[email protected]>
Link: https://lore.kernel.org/r/YAy9kJhM/rG8EQXC@watson
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
This commit is contained in:
Jeremy Figgins authored and Greg Kroah-Hartman committed 2021-01-26 15:15:31 +01:00
1 parent 6ee1d745b7
commit d8c6edfa3f
1 file changed
+11 -8
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drivers/usb/class/usblp.c
+11 -8
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@@ -1329,14 +1329,17 @@ 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);