On 28/04/16 04:54, Peter Chen wrote: > On Wed, Apr 27, 2016 at 01:59:44PM +0300, Roger Quadros wrote: >> 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; >> } >> ... >> } >> > > According to Jun, this framework still needs to improve (maybe small) even > using user work item for fully OTG, so the first step is let the drd > work well:) > Agreed. Until one OTG implementation is tested we can't really say it works :). cheers, -roger -- 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
