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Date:      Thu, 21 Dec 2017 08:19:43 -0800 (PST)
From:      "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net>
To:        bob prohaska <fbsd@www.zefox.net>
Cc:        "Jukka A. Ukkonen" <jau789@gmail.com>, freebsd-arm@freebsd.org
Subject:   Re: Disapearing pl2303 usb serial adapter on rpi2
Message-ID:  <201712211619.vBLGJhpM032044@pdx.rh.CN85.dnsmgr.net>
In-Reply-To: <20171221161120.GA20324@www.zefox.net>

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> On Wed, Dec 20, 2017 at 09:13:12PM +0200, Jukka A. Ukkonen wrote:
> > On 12/20/17 19:02, bob prohaska wrote:
> > > On an RPI2 at r326951 a pl2303 usb-serial adapter seems to be locking up
> > > after a few hours. In the past this could be rectified by using usbconfig
> > > to power cycle it, but now even that doesn't work. Apart from the serial
> > > device file vanishing from /dev there seems to be no other ill effect.
> > > Rebooting fixes the problem for minutes to hours.
> > > 
> > > There is no explict error report in dmesg, but when usbconfig tries to power
> > > cycle the adapter the console reports:
> > > 
> > > uhub_explore_handle_re_enumerate: Could not unconfigure device (ignored)
> > > usbd_req_re_enumerate: addr=9, set address failed! (USB_ERR_IOERROR, ignored)
> > > usbd_setup_device_desc: getting device descriptor at addr 9 failed, USB_ERR_IOERROR
> > > usbd_req_re_enumerate: addr=9, set address failed! (USB_ERR_STALLED, ignored)
> > > usbd_setup_device_desc: getting device descriptor at addr 9 failed, USB_ERR_STALLED
> > > 
> > > 
> > > A second RPI2 running r326747 is subject to the same lockup, but the adapter
> > > can be unstuck using usbconfig to power cycle it.
> > > 
> > > 
> > > Are there any diagnostics which could shed more light on the problem?
> > > 
> > > Thanks for reading,
> > > 
> > > bob prohaska
> > > 
> > > _______________________________________________
> > > freebsd-arm@freebsd.org mailing list
> > > https://lists.freebsd.org/mailman/listinfo/freebsd-arm
> > > To unsubscribe, send any mail to "freebsd-arm-unsubscribe@freebsd.org"
> > > 
> > 
> > 
> > 
> > 
> > So, my guess is that the poor RPI is unable to drive enough power
> > to your pl2303. Esp. when there are multiple USB devices draining
> > power you will eventually exceed the RPI's power output capacity.
> > As a result you will see a magically vanishing and reappearing USB
> > device.
> 
> The Pi is on a 2.5 amp power supply, the other usb loads are a keyboard,
> mouse and USB flash drive, so it's unlikely to be a power issue. The problem
> seems to have gotten worse with the latest -current, which is what motivated
> my post. It's been suggested to simply give up on pl2303 devices and use 
> ftdi but I've resisted the urge because the pl2303 adapters work fine on
> Mac OS and Raspbian. 
> 
> The adapters work correctly with Prolific's drivers and are not identified
> as impostors. Testing disclosed that unpowering the USB end of the adapter
> does not suffice to unstick it, but unpowering both ends does allow it to 
> reset. Hopefully it's an initialization issue. 

What do you mean by unpowering both ends?
If this is one of the serial adapters that has a power pin
to plug in with the Gnd/Rx/Tx pins I would highly recommend
you leave that power pin disconnected as connecting it can
lead to power supplies in parallel and "that is a bad thing".


> Thanks for reading!
> 
> bob prohaska
> 
-- 
Rod Grimes                                                 rgrimes@freebsd.org



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