linux-kernel - Re: [v2] musb: omap2430: do not assume balanced enable()/disable()

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Date:   Sat, 10 Sep 2016 06:07:50 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     Andreas Kemnade <andreas@...nade.info>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Bin Liu <b-liu@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-omap@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Kishon Vijay Abraham I <kishon@...com>
Subject: Re: [v2] musb: omap2430: do not assume balanced enable()/disable()

* Andreas Kemnade <andreas@...nade.info> [160910 04:27]:
> On Fri, 9 Sep 2016 16:40:15 -0700
> Tony Lindgren <tony@...mide.com> wrote:
> 
> > * Tony Lindgren <tony@...mide.com> [160909 14:33]:
> > > * Andreas Kemnade <andreas@...nade.info> [160909 14:22]:
> > > > We have two independant things:
> > > > 1. phy-twl4030-usb (and perhaps others) do not enable
> > > >   the phy enough to allow charging on pm_runtime_get().
> > > >   That is fixed by my phy-related patches.
> > > 
> > > OK
> > >
> > > > 2. phy_power_off/on() in called in an unbalanced way if
> > > >    it is called behind musb_platform_enable()/disable()
> > > >    as it happens in omap2430.c. Two ways to fix it:
> > > >    a) prevent phy_power_off()/on() to be called in
> > > >       an unbalanced way in omap240.c
> > > >    b) prevent musb_platform_enable()
> > > > 	      musb_platform_disable() to be called in an
> > > > 	      unbalanced way by fixing musb_core.c
> > > > 
> > > > Fixing 1. is enough on gta04 to fix charging and hide 2. enough to
> > > > have gadget working for the most common usecases. (not using
> > > > twl4030-charger would not work yet)
> > > > But in the longer term 2. has to be fixed too.
> > > 
> > > Sounds like option 2b here is the real fix.
> > 
> > And doing full option 2b would be intrusive because of musb_stop
> > also calling musb_platform_disable. Here's a suggested fix for
> > v4.8-rc cycle.
> > 
> musb_platform_disable() in musb_stop() seems to be balanced.
> 
> from my list in an earlier mail:
> musb_platform_disable() in musb_remove() called upon module removal
> 
> To my analysis this is odd because musb_stop() is also called indirectly
> upon removal.
> But topic that can be left for later.

OK will update the patch description. You probaby should attempt
to do a patch to make the calls paired as you already know what
needs to be done there..

> > Seems to work for me for omap3 torpedo using phy-twl4030-usb,
> > omap4 pandaboard es using phy-twl6030-usb and am335x beaglebone
> > black using dsps glue. Also PM runtime works on omap3.
> > 
> > This patch causes a slight merge conlict with Andrea's patches,
> > as listed in #1 above, but we should probably merge this first
> > as a fix. That is assuming it does not cause side effects to
> > Andrea's phy-twl4030-usb charger test case.
> > 
> Hmm, if the patch will gender-change me, then a clear NAK ;-)

Sorry typo there, s/Andrea/Andreas/, no need for other radical
changes :)

> > Can you guys please test? If things work I'll resend the
> > patch with proper tested-bys and acks.
> > 
> I tested the patch without any other musb/phy-fixes.
> No regressions. It fixes Gadget to be usable. Charging seems
> not to be totally stable. I will check my phy-patches
> on top of that again. 
> PM runtime probably still desires some work on it.
> But I give a clear Ack for merging this one first.

OK good to hear & thanks for testing. Let's see what Laurent
says.

Regards,

Tony