On 26/04/16 03:07, Jun Li wrote: > Hi > >> -----Original Message----- >> From: Roger Quadros [mailto:rogerq@xxxxxx] >> Sent: Monday, April 25, 2016 10:04 PM >> To: Jun Li <jun.li@xxxxxxx>; stern@xxxxxxxxxxxxxxxxxxx; balbi@xxxxxxxxxx; >> gregkh@xxxxxxxxxxxxxxxxxxx; peter.chen@xxxxxxxxxxxxx >> Cc: dan.j.williams@xxxxxxxxx; jun.li@xxxxxxxxxxxxx; >> mathias.nyman@xxxxxxxxxxxxxxx; tony@xxxxxxxxxxx; Joao.Pinto@xxxxxxxxxxxx; >> abrestic@xxxxxxxxxxxx; r.baldyga@xxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx; >> linux-kernel@xxxxxxxxxxxxxxx; linux-omap@xxxxxxxxxxxxxxx >> Subject: Re: [PATCH v6 09/12] usb: gadget: udc: adapt to OTG core >> >> Hi, >> >> On 21/04/16 09:38, Jun Li wrote: >>> Hi, >>> >>> ... >>>> >>>> /** >>>> + * usb_gadget_start - start the usb gadget controller and connect to >>>> +bus >>>> + * @gadget: the gadget device to start >>>> + * >>>> + * This is external API for use by OTG core. >>>> + * >>>> + * Start the usb device controller and connect to bus (enable pull). >>>> + */ >>>> +static int usb_gadget_start(struct usb_gadget *gadget) { >>>> + int ret; >>>> + struct usb_udc *udc = NULL; >>>> + >>>> + dev_dbg(&gadget->dev, "%s\n", __func__); >>>> + mutex_lock(&udc_lock); >>>> + list_for_each_entry(udc, &udc_list, list) >>>> + if (udc->gadget == gadget) >>>> + goto found; >>>> + >>>> + dev_err(gadget->dev.parent, "%s: gadget not registered.\n", >>>> + __func__); >>>> + mutex_unlock(&udc_lock); >>>> + return -EINVAL; >>>> + >>>> +found: >>>> + ret = usb_gadget_udc_start(udc); >>>> + if (ret) >>>> + dev_err(&udc->dev, "USB Device Controller didn't start: %d\n", >>>> + ret); >>>> + else >>>> + usb_udc_connect_control(udc); >>> >>> For drd, it's fine, but for real otg, gadget connect should be done by >>> loc_conn() instead of gadget start. >> >> It is upto the OTG state machine to call gadget_start() when it needs to >> connect to the bus (i.e. loc_conn()). I see no point in calling gadget >> start before. >> >> Do you see any issue in doing so? > > This is what OTG state machine does: > case OTG_STATE_B_PERIPHERAL: > otg_chrg_vbus(otg, 0); > otg_loc_sof(otg, 0); > otg_set_protocol(fsm, PROTO_GADGET); > otg_loc_conn(otg, 1); > break; > > You intend to abstract something common in this api when start gadget, > which should be called by otg_set_protocol(fsm, PROTO_GADGET); and > drd_set_protocol(fsm, PROTO_GADGET); right? > > So you may move usb_udc_connect_control(IMO usb_gadget_connect() > is better)out of usb_gadget_start(), then for drd: > > case OTG_STATE_B_PERIPHERAL: > drd_set_protocol(fsm, PROTO_GADGET); > otg_drv_vbus(otg, 0); > usb_gadget_connect(); OK. I understand now. I'll implement your suggestion. Thanks. cheers, -roger >>> >>>> + >>>> + mutex_unlock(&udc_lock); >>>> + >>>> + return ret; >>>> +} >>>> + >>>> +/** >>>> + * usb_gadget_stop - disconnect from bus and stop the usb gadget >>>> + * @gadget: The gadget device we want to stop >>>> + * >>>> + * This is external API for use by OTG core. >>>> + * >>>> + * Disconnect from the bus (disable pull) and stop the >>>> + * gadget controller. >>>> + */ >>>> +static int usb_gadget_stop(struct usb_gadget *gadget) { >>>> + struct usb_udc *udc = NULL; >>>> + >>>> + dev_dbg(&gadget->dev, "%s\n", __func__); >>>> + mutex_lock(&udc_lock); >>>> + list_for_each_entry(udc, &udc_list, list) >>>> + if (udc->gadget == gadget) >>>> + goto found; >>>> + >>>> + dev_err(gadget->dev.parent, "%s: gadget not registered.\n", >>>> + __func__); >>>> + mutex_unlock(&udc_lock); >>>> + return -EINVAL; >>>> + >>>> +found: >>>> + usb_gadget_disconnect(udc->gadget); >>> >>> Likewise, gadget disconnect also should be done by loc_conn() instead >>> of gadget stop. >>> >>>> + udc->driver->disconnect(udc->gadget); >>>> + usb_gadget_udc_stop(udc); >>>> + mutex_unlock(&udc_lock); >>>> + >>>> + return 0; >>>> +} >>>> + >>> >>> Li Jun >>> -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
