diff options
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | drivers/usb/core/message.c | 25 |
1 files changed, 4 insertions, 21 deletions
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c index 40bdb38e7bc..e12c5be1e0a 100644 --- a/drivers/usb/core/message.c +++ b/drivers/usb/core/message.c @@ -1133,29 +1133,10 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate) /* prevent submissions using previous endpoint settings */ usb_disable_interface(dev, iface); - /* 9.1.1.5 says: - * - * Configuring a device or changing an alternate setting - * causes all of the status and configuration values - * associated with endpoints in the affected interfaces to - * be set to their default values. This includes setting - * the data toggle of any endpoint using data toggles to - * the value DATA0. - * - * Some devices take this too literally and don't reset the data - * toggles if the new altsetting is the same as the old one (the - * command isn't "changing" an alternate setting). We will manually - * reset the toggles when the new and old altsettings are the same. - * Most devices won't need this, but fortunately it doesn't happen - * often. - */ - if (iface->cur_altsetting == alt) - manual = 1; iface->cur_altsetting = alt; /* If the interface only has one altsetting and the device didn't - * accept the request (or whenever the old altsetting is the same - * as the new one), we attempt to carry out the equivalent action + * accept the request, we attempt to carry out the equivalent action * by manually clearing the HALT feature for each endpoint in the * new altsetting. */ @@ -1202,7 +1183,9 @@ int usb_set_interface(struct usb_device *dev, int interface, int alternate) * * Because this affects multiple interfaces, avoid using this with composite * (multi-interface) devices. Instead, the driver for each interface may - * use usb_set_interface() on the interfaces it claims. Resetting the whole + * use usb_set_interface() on the interfaces it claims. Be careful though; + * some devices don't support the SET_INTERFACE request, and others won't + * reset all the interface state (notably data toggles). Resetting the whole * configuration would affect other drivers' interfaces. * * The caller must own the device lock. |