Hi, On 27/04/16 06:15, Peter Chen wrote: > On Tue, Apr 26, 2016 at 04:21:07PM +0800, Peter Chen wrote: >> On Tue, Apr 26, 2016 at 07:00:22AM +0000, Jun Li wrote: >>> Hi >>> >>>> -----Original Message----- >>>> From: Peter Chen [mailto:hzpeterchen@xxxxxxxxx] >>>> Sent: Tuesday, April 26, 2016 2:28 PM >>>> To: Jun Li <jun.li@xxxxxxx> >>>> Cc: Roger Quadros <rogerq@xxxxxx>; stern@xxxxxxxxxxxxxxxxxxx; >>>> balbi@xxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; peter.chen@xxxxxxxxxxxxx; >>>> 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 07/12] usb: otg: add OTG/dual-role core >>>> >>>> On Tue, Apr 26, 2016 at 05:11:36AM +0000, Jun Li wrote: >>>>> Hi >>>>> >>>>>> -----Original Message----- >>>>>> From: Peter Chen [mailto:hzpeterchen@xxxxxxxxx] >>>>>> Sent: Tuesday, April 26, 2016 11:47 AM >>>>>> To: Jun Li <jun.li@xxxxxxx> >>>>>> Cc: Roger Quadros <rogerq@xxxxxx>; stern@xxxxxxxxxxxxxxxxxxx; >>>>>> balbi@xxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; >>>>>> peter.chen@xxxxxxxxxxxxx; 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 07/12] usb: otg: add OTG/dual-role core >>>>>> >>>>>> On Tue, Apr 26, 2016 at 02:07:56AM +0000, Jun Li wrote: >>>>>>>> +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; >>>>>>>> + >>>>>>>> + if ((otg->caps->hnp_support || otg->caps->srp_support || >>>>>>>> + otg->caps->adp_support) && !config->otg_work) >>>>>>>> + dev_info(dev, "otg: limiting to dual-role\n"); >>>>>>> >>>>>>> dev_err, this should be an error. >>>>>> >>>>>> The condition may be wrong, but it is an information to show that >>>>>> current OTG is dual-role. >>>>> >>>>> This should not happen in any correct design, I even doubt if we >>>>> should try to continue by "downgrade" it to be duel role, currently >>>>> the only example user is dual role, so doing like this can't be tested >>>>> by real case, this downgrade is not so easy like we image, at least >>>>> for chipidea otg driver, simply replace a queue worker may not work, >>>>> as we have much more difference between the 2 configs. >>>>> >>>> >>>> Would you show more why chipidea can't work just replace the work item, >>>> and see if anything we still can improve for this framework? >>> >>> In real OTG, we need enable AVV irq, >> >> Enable and Handling AVV is platform stuff. In this framework, we are >> focus on how otg device manages host and gadget together, and the state >> machine when the related otg event occurs. >> >>> but for duel role, nobody care/handle, >>> there are much more resource required for OTG: timers, hnp polling, >>> otg test device handling... >> >> They are common things for fully OTG fsm, you can move them >> to common code (In fact, hnp polling handling is already common code). >> >>> >>> with current design, chipidea driver can support real OTG with its own >>> queue worker, or DRD with Roger's drd work item if config is correct. >>> >>> But improve something to work on a *wrong* config will make it complicated >>> and does not make much sense IMO. >>> >> >> What does above "config" you mean? >> >> If the configure is fully OTG, you can choose different state machine, >> eg otg_statemachine, if you find it is hard for chipidea to use this >> framework, just list the reason, and see if we can improve. >> > > Roger, after discussing with Jun off line, we think usb_otg_register > should return -ENOTSUPP if platform is OTG capabilities (HNP || SRP || > ADP), since this patch set does not cover fully otg features, the users But this series isn't preventing full otg implementation. You can still do that via config->otg_work. I can modify the following condition to return -ENOTSUPP instead of defaulting to dual-role struct usb_otg *usb_otg_register(...) { ... if ((otg->caps->hnp_support || otg->caps->srp_support || otg->caps->adp_support) && !config->otg_work) { dev_err(dev, "otg: otg_work must be provided for OTG support\n"); return -ENOTSUPP; } ... } Is this sufficient? > should not be confused when try to implement fully otg using this > framework. > > Later, after your patch set is merged, we can add fully OTG features > using this framework, and remove this check. > > What's your opinion? > -- cheers, -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
