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

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Date:	Wed, 3 Aug 2016 16:54:36 +0200
From:	Andreas Kemnade <andreas@...nade.info>
To:	Tony Lindgren <tony@...mide.com>
Cc:	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, letux-kernel@...nphoenux.org
Subject: Re: [PATCH] musb: omap2430: do not assume balanced
 enable()/disable()

On Tue, 2 Aug 2016 23:30:16 -0700
Tony Lindgren <tony@...mide.com> wrote:

> * Andreas Kemnade <andreas@...nade.info> [160802 08:14]:
> > On Tue, 2 Aug 2016 03:33:34 -0700
> > Tony Lindgren <tony@...mide.com> wrote:
> > 
> > > * Andreas Kemnade <andreas@...nade.info> [160729 11:14]:
> > > > The code assumes that omap2430_musb_enable() and
> > > > omap2430_musb_disable() is called in a balanced way. The
> > > > That fact is broken by the fact that musb_init_controller()
> > > > calls musb_platform_disable() to switch from unknown state to
> > > > off state.
> > > 
> > > OK, some spelling issues with the above paragraph though :)
> > > 
> > > > That means that phy_power_off() is called first so that
> > > > phy->power_count gets -1 and the phy is not enabled on
> > > > phy_power_on(). In the probably common case of using the
> > > > phy_twl4030, that prevents also charging the battery and so
> > > > makes further kernel debugging hard.
> > > 
> > > Is this with v4.7 kernel? Also, care to describe how you hit this
> > > and on which hardware? Just wondering..
> > 
> > I got this error on the Openphoenux GTA04 phone. It has a DM3730
> > SoC and a TPS65950 companion. Severe charging problems were already
> > observed with the 4.4rc1. I do not know if that already was exactly
> > *this* problem. I have debugged and patched the v4.7 kernel.
> 
> OK thanks for the info.
> 
> > How I hit the problem: Just boot an that device and try to charge
> > via usb.
> 
> OK so it's the twl4030 charger then I guess.
> 
yes, besides from causing usb gadget problems, it has side effect
towards the twl4030 charger.

> > Should I resubmit the patch with an extended commit message?
> 
> Well yeah it might be worth describing that it's the twl4030
> charger that otherwise does not work properly.
> 
Ok, will resend a better commit message.

Regards,
Andreas Kemnade

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