On Thu, Mar 19, 2015 at 12:30:46PM +0200, Roger Quadros wrote:
> On 19/03/15 10:26, Li Jun wrote:
> > On Wed, Mar 18, 2015 at 03:55:57PM +0200, Roger Quadros wrote:
> >> The OTG core instantiates the OTG Finite State Machine
> >> per OTG controller and manages starting/stopping the
> >> host and gadget controllers based on the bus state.
> >>
> >> It provides APIs for the following tasks
> >>
> >> - Registering an OTG capable controller
> >> - Registering Host and Gadget controllers to OTG core
> >> - Providing inputs to and kicking the OTG state machine
> >>
> >> TODO:
> >> - sysfs interface to allow application inputs to OTG state machine
> >> - otg class?
> >>
> >> Signed-off-by: Roger Quadros <rog...@ti.com>
> >> ---
> >> +struct otg_data {
> >> + struct device *dev; /* HCD & GCD's parent device */
> >> +
> >> + struct otg_fsm fsm;
> >> + /* HCD, GCD and usb_otg_state are present in otg_fsm->otg
> >> + * HCD is bus_to_hcd(fsm->otg->host)
> >> + * GCD is fsm->otg->gadget
> >> + */
> >> + struct otg_fsm_ops fsm_ops; /* private copy for override */
> >> + struct usb_otg otg;
> >> + struct usb_hcd *shared_hcd; /* if shared HCD registered */
> >> +
> >> + /* saved hooks to OTG device */
> >> + int (*start_host)(struct otg_fsm *fsm, int on);
> >> + int (*start_gadget)(struct otg_fsm *fsm, int on);
> >> +
> >> + struct list_head list;
> >> +
> >> + struct work_struct work; /* OTG FSM work */
> >> + struct workqueue_struct *wq;
> >> +
> >> + struct otg_timer timers[NUM_OTG_FSM_TIMERS];
> >> +
> >> + bool fsm_running;
> >> + bool gadget_can_start; /* OTG FSM says gadget can start */
> >> + bool host_can_start; /* OTG FSM says host can start */
> >
> > Do not understand above 2 *_can_start flags from the patch, which are set
> > only when you really start host/gadget, to prevent host/gadget driver to
> > start it out of otg fsm control?
>
> host_can_start is used only by this driver in the following _unlikely_
> condition
> and could probably be got rid of.
> - Primary HCD and gadget registers
> - OTG FSM signals host to start but it can't start as shared HCD isn't yet
> registered.
> so we set this flag.
> - when shared HCD registers, we check the flag and explicitly start both the
> host controllers.
>
> gadget_can_start is used by the gadget driver through the
> usb_otg_gadget_can_start() API.
> This is needed because gadget might start at a later time depending on either
> - gadget function driver loads
I think it should be loaded before kick off OTG fsm.
> - userspace enables softconnect.
Why use the input of softconnect in userspace? I suppose all inputs should be
in scope/defined by OTG spec(a_bus_req, b_bus_req...).
So it's possible the gadget has not been started(pull up DP) while the OTG fsm
is in b_peripheral state? If yes, it's breaking OTG spec 7.2.3:
...
When a high-speed capable B-device enters this state it shall enable its pull-up
on D+. After the B-device enables its pull-up, it shall monitor the state of the
bus to determine if a bus reset is being signaled by the A-device.
...
So for B-device, it should start gadget(pull up DP) if detects valid BSV vbus,
that's the only condition.
Li Jun
>
> >
> > Li Jun
> >> +
> >> + /* use otg->fsm.lock for serializing access */
> >> +};
> >> +
> >> + * Can be called in IRQ context.
> >> + */
> >> +void usb_otg_sync_inputs(struct otg_fsm *fsm)
> >> +{
> >> + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
> >> +
> >> + /* Don't kick FSM till it has started */
> >> + if (!otgd->fsm_running)
> >> + return;
> >> +
> >> + /* Kick FSM */
> >> + queue_work(otgd->wq, &otgd->work);
> >> +}
> >> +EXPORT_SYMBOL_GPL(usb_otg_sync_inputs);
> >> +
> >> +/**
> >> + * usb_otg_kick_fsm - Kick the OTG state machine
> >> + * @hcd_gcd_device: Host/Gadget controller device
> >> + *
> >> + * Used by USB host/device stack to sync OTG related
> >> + * events to the OTG state machine.
> >> + * e.g. change in host_bus->b_hnp_enable, gadget->b_hnp_enable
> >> + *
> > There are quite a few otg fsm variables which should be updated when
> > events/interrupts(b_conn, a_srp_det, ...) occur, how is your plan to
> > update them? Still rely on specific controller driver irq handler to
> > capture all those events and update them?
>
> Yes, my plan was that the OTG controller driver will handle those
> interrupts, update otg_fsm members and call usb_otg_sync_inputs() to
> notify the OTG FSM.
>
> cheers,
> -roger
>
> >
> > Li Jun
> >> + * Returns: 0 on success, error value otherwise.
> >> + */
> >> +int usb_otg_kick_fsm(struct device *hcd_gcd_device)
> >> +{
> >> + struct otg_data *otgd;
> >> +
> >> + mutex_lock(&otg_list_mutex);
> >> + otgd = usb_otg_device_get_otgd(hcd_gcd_device->parent);
> >> + if (!otgd) {
> >> + dev_err(hcd_gcd_device, "%s: invalid host/gadget device\n",
> >> + __func__);
> >> + mutex_unlock(&otg_list_mutex);
> >> + return -ENODEV;
> >> + }
> >> +
> >> + mutex_unlock(&otg_list_mutex);
> >> + usb_otg_sync_inputs(&otgd->fsm);
> >> +
> >> + return 0;
> >> +}
> >> +EXPORT_SYMBOL_GPL(usb_otg_kick_fsm);
> >> --
> >> 2.1.0
> >>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
