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

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Date:	Thu, 4 Aug 2016 18:31:29 +0200
From:	Andreas Kemnade <andreas@...nade.info>
To:	Tony Lindgren <tony@...mide.com>
Cc:	"H. Nikolaus Schaller" <hns@...delico.com>, Bin Liu <b-liu@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linux USB Mailing List <linux-usb@...r.kernel.org>,
	linux-omap <linux-omap@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Discussions about the Letux Kernel 
	<letux-kernel@...nphoenux.org>
Subject: Re: [Letux-kernel] [PATCH v2] musb: omap2430: do not assume
 balanced enable()/disable()

Hi,

On Thu, 4 Aug 2016 07:29:19 -0700
Tony Lindgren <tony@...mide.com> wrote:

> Hi,
> 
> * H. Nikolaus Schaller <hns@...delico.com> [160803 10:07]:
> > All this prevents detection of cable plugin-events and VBUS
> > measurement and setting OTG_EN before charging is attempted.
> 
> So I gave this patch a try but it now blocks all deeper SoC idle
> states as the PHY stays active. I think the real fix is to make
> sure the charger behaves independent of the USB PHY state. So
> probably this needs to be fixed in phy-twl4030-usb.c and
> twl4030_charger.c instead. Now it sounds like we're also shutting
> down the charger with the USB PHY.
> 
Then there is another power management issue. The patch is not about
fixing every pm issue in musb. That is not only about charging, it is
about enabling/disabling() the phy unbalanced:
Again what happens here without the patch:

musb will be initialized:
omap2430_musb_disable()
   calls phy_power_off(), phy will be disabled,
	phy->power_count goes to -1.

gadget driver is loaded.
musb_start() is called
    omap2430_musb_enable() is called
	calls phy_power_on(),
	phy->power_count goes to 0,
	phy is not powered on because power_count != 1
-> no gadget working, no charging.

Regards
Andreas