> -----Original Message----- > From: Peter Chen [mailto:hzpeterchen@xxxxxxxxx] > Sent: Wednesday, May 25, 2016 10:44 AM > To: Roger Quadros <rogerq@xxxxxx> > Cc: peter.chen@xxxxxxxxxxxxx; balbi@xxxxxxxxxx; tony@xxxxxxxxxxx; > gregkh@xxxxxxxxxxxxxxxxxxx; dan.j.williams@xxxxxxxxx; > mathias.nyman@xxxxxxxxxxxxxxx; Joao.Pinto@xxxxxxxxxxxx; > sergei.shtylyov@xxxxxxxxxxxxxxxxxx; jun.li@xxxxxxxxxxxxx; > grygorii.strashko@xxxxxx; yoshihiro.shimoda.uh@xxxxxxxxxxx; > robh@xxxxxxxxxx; nsekhar@xxxxxx; b-liu@xxxxxx; linux-usb@xxxxxxxxxxxxxxx; > linux-omap@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > devicetree@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v8 08/14] usb: otg: add OTG/dual-role core > > On Tue, May 24, 2016 at 12:45:46PM +0300, Roger Quadros wrote: > > Hi Peter, > > > > I have one question here. Please see below. > > > > On 13/05/16 13:03, Roger Quadros wrote: > > > It provides APIs for the following tasks > > > > > > - Registering an OTG/dual-role capable controller > > > - Registering Host and Gadget controllers to OTG core > > > - Providing inputs to and kicking the OTG state machine > > > > > > Provide a dual-role device (DRD) state machine. > > > DRD mode is a reduced functionality OTG mode. In this mode we don't > > > support SRP, HNP and dynamic role-swap. > > > > > > In DRD operation, the controller mode (Host or Peripheral) is > > > decided based on the ID pin status. Once a cable plug (Type-A or > > > Type-B) is attached the controller selects the state and doesn't > > > change till the cable in unplugged and a different cable type is > > > inserted. > > > > > > As we don't need most of the complex OTG states and OTG timers we > > > implement a lean DRD state machine in usb-otg.c. > > > The DRD state machine is only interested in 2 hardware inputs 'id' > > > and 'b_sess_vld'. > > > > > > Signed-off-by: Roger Quadros <rogerq@xxxxxx> > > > --- > > > drivers/usb/common/Makefile | 2 +- > > > drivers/usb/common/usb-otg.c | 1042 > ++++++++++++++++++++++++++++++++++++++++++ > > > drivers/usb/core/Kconfig | 4 +- > > > include/linux/usb/gadget.h | 2 + > > > include/linux/usb/hcd.h | 1 + > > > include/linux/usb/otg-fsm.h | 7 + > > > include/linux/usb/otg.h | 154 ++++++- > > > 7 files changed, 1206 insertions(+), 6 deletions(-) create mode > > > 100644 drivers/usb/common/usb-otg.c > > > > > > > <snip> > > > > > + > > > +/** > > > + * usb_otg_register() - Register the OTG/dual-role device to OTG > > > +core > > > + * @dev: OTG/dual-role controller device. > > > + * @config: OTG configuration. > > > + * > > > + * Registers the OTG/dual-role controller device with the USB OTG > core. > > > + * > > > + * Return: struct usb_otg * if success, ERR_PTR() if error. > > > + */ > > > +struct usb_otg *usb_otg_register(struct device *dev, > > > + struct usb_otg_config *config) { > > > + struct usb_otg *otg; > > > + struct otg_wait_data *wait; > > > + int ret = 0; > > > + > > > + if (!dev || !config || !config->fsm_ops) > > > + return ERR_PTR(-EINVAL); > > > + > > > + /* already in list? */ > > > + mutex_lock(&otg_list_mutex); > > > + if (usb_otg_get_data(dev)) { > > > + dev_err(dev, "otg: %s: device already in otg list\n", > > > + __func__); > > > + ret = -EINVAL; > > > + goto unlock; > > > + } > > > + > > > + /* allocate and add to list */ > > > + otg = kzalloc(sizeof(*otg), GFP_KERNEL); > > > + if (!otg) { > > > + ret = -ENOMEM; > > > + goto unlock; > > > + } > > > + > > > + otg->dev = dev; > > > + otg->caps = config->otg_caps; > > > > Here, we should be checking if user needs to disable any OTG features. > > So, > > > > if (dev->of_node) > > of_usb_update_otg_caps(dev->of_node, &otg->caps); > > > > Do you agree? > > This means we need to change otg->caps from 'struct usb_otg_caps *caps;' > > to 'struct usb_otg_caps caps;' so that we can modify the local copy > > instead of the one passed by the OTG controller. > > Why can't modify the one from OTG controller directly? Yes, if user wants to disable any OTG features, this should have been done in 'config->otg_caps', if not, 'config->otg_caps' from controller driver is invalid and making no sense. > > > > > We can also move of_usb_update_otg_caps() to otg.h. > > > > We will also need to modify the udc-core code so that it sets > > gadget->otg_caps to the modified otg_caps from the OTG core. This will > > ensure that the right OTG descriptors are sent. > > > > So we will have to introduce an API. > > > > struct usb_otg_caps *usb_otg_get_otg_caps(struct device *otg_dev) > > > > And in udc-core.c, > > > > static int udc_bind_to_driver(struct usb_udc *udc, struct > > usb_gadget_driver *driver) { .. > > ret = driver->bind(udc->gadget, driver); > > if (ret) > > goto err1; > > > > /* If OTG, the otg core starts the UDC when needed */ > > if (udc->gadget->otg_dev) { > > + udc->gadget->is_otg = true; > > gadget->is_otg is only set to true if fully OTG is supported and it > needs to send OTG descriptors at this case. DRD devices should not send > OTG descriptors. > > > + udc->gadget->otg_caps = usb_otg_get_otg_caps(udc->gadget- > >otg_dev); > > Getting otg capabilities should be prior to driver->bind since > usb_otg_descriptor_init is called at that. Besides, Gadget driver may be > probed before otg driver is registered > > I am wonder if we can implement defer probe for gadget/udc/host driver if > otg driver is not probed, in that case, some designs can be simpler like > wait list in otg driver. I even don't see much benefit of this kind of random order of OTG/HCD/GADGET registration, anyway OTG register can be done firstly. HCD and GADGET are both separated drivers, but OTG is newly added and what we need is just a registration in controller driver. > > > mutex_unlock(&udc_lock); > > usb_otg_register_gadget(udc->gadget, &otg_gadget_intf); > > mutex_lock(&udc_lock); > > } else { > > ret = usb_gadget_udc_start(udc); > > if (ret) { > > driver->unbind(udc->gadget); > > goto err1; > > } > > usb_udc_connect_control(udc); > > } > > .. > > } > > > > What do you say? > > > > regards, > > -roger > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-usb" > > in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo > > info at http://vger.kernel.org/majordomo-info.html > > -- > > Best Regards, > Peter Chen -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
