diff options
| -rw-r--r-- | include/linux/usb/composite.h | 8 | ||||
| -rw-r--r-- | include/linux/usb/gadget.h | 9 |
2 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/usb/composite.h b/include/linux/usb/composite.h index 6014340ba980..af3cd2aae4bc 100644 --- a/include/linux/usb/composite.h +++ b/include/linux/usb/composite.h @@ -35,6 +35,14 @@ * are ready. The control transfer will then be kept from completing till * all the function drivers that requested for USB_GADGET_DELAYED_STAUS * invoke usb_composite_setup_continue(). + * + * NOTE: USB_GADGET_DELAYED_STATUS must not be used in UDC drivers: they + * must delay completing the status stage for 0-length control transfers + * regardless of the whether USB_GADGET_DELAYED_STATUS is returned from + * the gadget driver's setup() callback. + * Currently, a number of UDC drivers rely on USB_GADGET_DELAYED_STATUS, + * which is a bug. These drivers must be fixed and USB_GADGET_DELAYED_STATUS + * must be contained within the composite framework. */ #define USB_GADGET_DELAYED_STATUS 0x7fff /* Impossibly large value */ diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h index 75bda0783395..6532beb587b1 100644 --- a/include/linux/usb/gadget.h +++ b/include/linux/usb/gadget.h @@ -711,6 +711,15 @@ static inline int usb_gadget_check_config(struct usb_gadget *gadget) * get_interface. Setting a configuration (or interface) is where * endpoints should be activated or (config 0) shut down. * + * The gadget driver's setup() callback does not have to queue a response to + * ep0 within the setup() call, the driver can do it after setup() returns. + * The UDC driver must wait until such a response is queued before proceeding + * with the data/status stages of the control transfer. + * + * NOTE: Currently, a number of UDC drivers rely on USB_GADGET_DELAYED_STATUS + * being returned from the setup() callback, which is a bug. See the comment + * next to USB_GADGET_DELAYED_STATUS for details. + * * (Note that only the default control endpoint is supported. Neither * hosts nor devices generally support control traffic except to ep0.) * |