linux-kernel - Re: [PATCH] usb: musb: core: Disable the Interrupts till BABBLE is fully handled

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Date:	Tue, 18 Nov 2014 15:17:34 -0600
From:	Felipe Balbi <balbi@...com>
To:	George Cherian <george.cherian@...com>
CC:	<balbi@...com>, <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<bigeasy@...utronix.de>
Subject: Re: [PATCH] usb: musb: core: Disable the Interrupts till BABBLE is
 fully handled

On Fri, Nov 14, 2014 at 01:54:46PM +0530, George Cherian wrote:
> Disable the MUSB interrupts till MUSB is recovered fully from BABBLE
> condition. There are chances that we could get multiple interrupts
> till the time the babble recover work gets scheduled. Sometimes
> this could even end up in an endless loop making MUSB itself unusable.
> 
> Reported-by: Felipe Balbi <balbi@...com>	
> Signed-off-by: George Cherian <george.cherian@...com>

while this helps the situation it doesn't solve the problem I'm having
with testusb on BBB when host port is connected to peripheral port on
the same BBB.

I still have:

# ./testusb -t 13 -c 10 -s 2048 -a
unknown speed   /dev/bus/usb/002/004    0
[  114.811407] usbtest 2-1:3.0: set altsetting to 0 failed, -71
/dev/bus/usb/002/004 test 13 --> 71 (error 71)
[  114.862387] CAUTION: musb: Babble Interrupt Occurred
[  114.868132] usb 2-1: USB disconnect, device number 4
[  114.961491] musb-hdrc musb-hdrc.1.auto: Restarting MUSB to recover from Babble
[  115.430829] usb 2-1: new high-speed USB device number 5 using musb-hdrc
[  115.573471] zero gadget: high-speed config #3: source/sink
[  115.584014] usbtest 2-1:3.0: Linux gadget zero
[  115.588682] usbtest 2-1:3.0: high-speed {control in/out bulk-in bulk-out} tests (+alt)

I think the driver is mis-detecting Babble. A babble only occurs when
the device side tries to move data without the host asking for anything.

-- 
balbi

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