> -----Original Message----- > From: Paul Fertser [mailto:fercerpav@xxxxxxxxx] > Sent: Thursday, May 08, 2014 9:09 PM > To: Gupta Suresh-B42813 > Cc: balbi@xxxxxx; Li Yang-Leo-R58472; linux-usb@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] usb: gadget: fsl: check vbus presence on probe > > Hi, > > On Thu, May 08, 2014 at 02:30:39PM +0000, suresh.gupta@xxxxxxxxxxxxx > wrote: > > As per my limited knowledge, the purpose of OTGSC_STS_B_SESSION_VALID > > bit is to tell either VBUS is above the B session valid threshold and > > which comes only Host is attached. > > Yes, that matches the datasheet I've read. > > > And Host might be attach after system bootup or after driver > > initialization. So putting this check in probe will not help much. > > If the host is attached after the driver was initialised, the interrupt > will trigger and the driver will get notified that VBUS appeared and > everything will go smooth, at least that's how it should work (I do not > have any board handy to real-life check that, but AFAICT that's the > intent of the current code). If is go through the code flow starting from usb_composite_probe the sequence is usb_composite_probe->usb_gadget_probe_driver->udc_bind_to_driver-> udc_bind_to_driver->usb_gadget_udc_start->fsl_udc_start->usbcmd=RUN udc_bind_to_driver->usb_gadget_connect->fsl_pullup The function fsl_pullup make usbcmd=STOP if my fix is not there and if controller is stopped we do not get any interrupt. > > I actually do not have any iMX demoboards at all, I've only got some > custom-designed i.MX25 boards where I can't control VBUS, it's > permanently pulled up. > > But I was fixing the problem that was clearly, 100% reproducibly > happening when VBUS was applied before the interrupt was configured. So Wait a minute, are you using OTG. If your VBUS is permanently pulled up, that means you are only Gadget(I might miss something) then why you use OTG mode. > what exactly do you mean here? Do you mean this check I've added doesn't > fix the bug? Or do you mean this bug should be fixed somehow else? Or do What expertly my concern is, probe is not proper place to check VBUS valid. I think we should wait to hear what Balbi has to say. > you mean there's no bug in the first place and my board doesn't work > because of something else? > > -- > Be free, use free (http://www.gnu.org/philosophy/free-sw.html) software! > mailto:fercerpav@xxxxxxxxx -- 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
