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

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Message-ID: <20141125144909.GD6360@saruman>
Date:	Tue, 25 Nov 2014 08:49:09 -0600
From:	Felipe Balbi <balbi@...com>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
CC:	<balbi@...com>, George Cherian <george.cherian@...com>,
	<gregkh@...uxfoundation.org>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: musb: core: Disable the Interrupts till BABBLE is
 fully handled

Hi,

On Tue, Nov 25, 2014 at 09:24:46AM +0100, Sebastian Andrzej Siewior wrote:
> On 11/25/2014 02:09 AM, Felipe Balbi wrote:
> > 
> >> I *think* for some reason the host did not really receive ep0
> >> set_config request as planned. And device's answer is probably then
> >> interpreted as data which is not expected (as Felipe said "device side
> >> tries to move data without the host asking for anything").
> > 
> > that's definitely a bug, unfortunately I can't think of any Erratum
> > right now.
> 
> maybe there will be a new one :)

maybe :-)

> >>>> That's certainly babble :-)
> >>>
> >>> Certainly! But musb shouldn't fall over or lock up because of it,
> >>> should it?
> >>
> >> No and the patch fixes the issue. The strange thing is that it only
> >> happens on the same device. Not if you connect host<->device with two
> >> boards.
> > 
> > probably some crap going on within the interconnect when both instances
> > are used.
> Either that or something is synchronized since both instances use
> probably the same clock source. But there is definitely something
> switched off since it does not happen without PM enabled.

ok, then we can blame somebody else. Good. We're off the hook, next!

I think it might be wise to look at which clocks the USB block is using
and making sure drivers/clk/ti/ waits for clocks to be stable before
returning control to caller.

cheers ;-)

-- 
balbi

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