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

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Date:	Wed, 3 Aug 2016 19:07:09 +0200
From:	"H. Nikolaus Schaller" <hns@...delico.com>
To:	Andreas Kemnade <andreas@...nade.info>
Cc:	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>,
	Tony Lindgren <tony@...mide.com>,
	Discussions about the Letux Kernel 
	<letux-kernel@...nphoenux.org>
Subject: Re: [Letux-kernel] [PATCH v2] musb: omap2430: do not assume balanced enable()/disable()

> Am 03.08.2016 um 17:38 schrieb Andreas Kemnade <andreas@...nade.info>:
> 
> The code assumes that omap2430_musb_enable() and
> omap2430_musb_disable() are called in a balanced way.
> That fact is broken by the fact that musb_init_controller() calls
> musb_platform_disable() to switch from unknown state to off state
> on initialisation.
> 
> 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().
> So when usb gadget is started the phy is not powered on.
> Depending on the phy used that caused various problems.
> Besides of causing usb problems, that can also have side effects.
> 
> In the case of using the phy_twl4030, that prevents also charging
> the battery via usb (using twl4030_charger) and so makes further
> kernel debugging hard.
> The problem was seen with 4.7 on an openphoenux gta04. It has a DM3730
> SoC and a TPS65950 companion.  phy->power never became 1

s/TPS65950/TPS65950 (twl4030)/

> and so the usb did get powered on.

s/did get/did not get/

maybe add:

All this prevents detection of cable plugin-events and VBUS measurement
and setting OTG_EN before charging is attempted.

> 
> The patch prevents phy_power_off() from being called when
> it is already off.
> 
> Signed-off-by: Andreas Kemnade <andreas@...nade.info>
> ---
> changes in v2:
> improved commit message
> 
> drivers/usb/musb/omap2430.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/musb/omap2430.c b/drivers/usb/musb/omap2430.c
> index 0b4cec9..c1a2b7b 100644
> --- a/drivers/usb/musb/omap2430.c
> +++ b/drivers/usb/musb/omap2430.c
> @@ -413,9 +413,10 @@ static void omap2430_musb_disable(struct musb *musb)
> 	struct device *dev = musb->controller;
> 	struct omap2430_glue *glue = dev_get_drvdata(dev->parent);
> 
> -	if (!WARN_ON(!musb->phy))
> -		phy_power_off(musb->phy);
> -
> +	if (glue->enabled) {
> +		if (!WARN_ON(!musb->phy))
> +			phy_power_off(musb->phy);
> +	}
> 	if (glue->status != MUSB_UNKNOWN)
> 		omap_control_usb_set_mode(glue->control_otghs,
> 			USB_MODE_DISCONNECT);
> -- 
> 2.1.4
> 
> _______________________________________________
> http://projects.goldelico.com/p/gta04-kernel/
> Letux-kernel mailing list
> Letux-kernel@...nphoenux.org
> http://lists.goldelico.com/mailman/listinfo.cgi/letux-kernel

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