diff options
| author | Jeremy Figgins <kernel@jeremyfiggins.com> | 2021-01-23 18:21:36 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-01-26 15:15:31 +0100 |
| commit | d8c6edfa3f4ee0d45d7ce5ef18d1245b78774b9d (patch) | |
| tree | b8c3c0acd7fa904ea98939dac057ecf58ccb0639 /drivers/usb/class/usblp.c | |
| parent | 6ee1d745b7c9fd573fba142a2efdad76a9f1cb04 (diff) | |
USB: usblp: don't call usb_set_interface if there's a single alt
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>
Diffstat (limited to 'drivers/usb/class/usblp.c')
| -rw-r--r-- | drivers/usb/class/usblp.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/drivers/usb/class/usblp.c b/drivers/usb/class/usblp.c index 134dc2005ce9..c9f6e9758288 100644 --- a/drivers/usb/class/usblp.c +++ b/drivers/usb/class/usblp.c @@ -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); |