Re: [PATCH] usb-musb: keep VBUS on when device is disconnected

Path	csiph.com!news.redatomik.org!aioe.org!news.servidellagleba.it!bofh.it!news.nic.it!robomod
From	Bin Liu <b-liu@ti.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] usb-musb: keep VBUS on when device is disconnected
Date	Mon, 27 Mar 2017 19:20:02 +0200
Message-ID	<tpGtc-34b-17@gated-at.bofh.it> (permalink)
References	<tlipr-wL-1@gated-at.bofh.it> <toCBj-5D8-5@gated-at.bofh.it> <toOj7-5Ya-5@gated-at.bofh.it> <tpCpA-8bK-15@gated-at.bofh.it> <tpCIX-cb-35@gated-at.bofh.it> <tpE81-11f-13@gated-at.bofh.it> <tpFGO-2pv-27@gated-at.bofh.it> <tpGtc-34b-19@gated-at.bofh.it>
Dkim-Signature	v=1; a=rsa-sha256; c=relaxed/simple; d=ti.com; s=ti-com-17Q1; t=1490634934; bh=uKNyqwR4FcUystCfxN69yhNzlptU5UWHlfqal4vpgEI=; h=Date:From:To:CC:Subject:References:In-Reply-To; b=LMmw8UDyV/0KRDzKRk9BPgbkrr2m5XAzHV15v1e7xxOXu5mnudriyH5+frHLcEyV3 9FlWrt73J1XZhkF6wufoeKKqI021TxcSnm1zwZK4KuBfcCUOcKwBFBVxmWBjEN2XGC 28wAdumt1m5/VfHehekckkDmy+FlNM1kUAbfo1LQ=
Mail-Followup-To	Bin Liu <b-liu@ti.com>, Tony Lindgren <tony@atomide.com>, Moreno Bartalucci <moreno.bartalucci@tecnorama.it>, Lars Melin <larsm17@gmail.com>, "linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>, "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Alessio Igor Bogani <abogani@kernel.org>
MIME-Version	1.0
Content-Type	text/plain; charset="utf-8"
Content-Disposition	inline
Content-Transfer-Encoding	8bit
User-Agent	Mutt/1.5.21 (2010-09-15)
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	26
Organization	linux.* mail to news gateway
X-Original-Cc	Moreno Bartalucci <moreno.bartalucci@tecnorama.it>, Lars Melin <larsm17@gmail.com>, "linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>, "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Alessio Igor Bogani <abogani@kernel.org>
X-Original-Date	Mon, 27 Mar 2017 12:15:34 -0500
X-Original-Message-ID	<20170327171534.GA4403@uda0271908>
X-Original-References	<20170315140801.97230-1-moreno.bartalucci@tecnorama.it> <20170324185836.GC19814@uda0271908> <2d10809f-d482-ffa9-30b7-8785e94ab102@gmail.com> <00882633-3F61-4010-A4D2-D04473282B10@tecnorama.it> <20170327131701.GA12674@uda0271908> <20170327143049.GG10760@atomide.com> <63FD9E13-2B70-485C-80A7-206BEC16905A@tecnorama.it> <20170327165946.GL10760@atomide.com>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1610007

Show key headers only | View raw

On Mon, Mar 27, 2017 at 09:59:47AM -0700, Tony Lindgren wrote:
> * Moreno Bartalucci <moreno.bartalucci@tecnorama.it> [170327 09:23]:
> > If I understood your patch, however, if the device (anyone, not just my one) takes longer to switch, VBUS is deasserted anyway.
> 
> Yeah some of them can take at least 10 seconds even to enumerate.
> So probably we need to have to have some longer timeout set for
> OTG_STATE_A_WAIT_BCON, like 20 or 30 seconds.
> 
> > Although this patch is working for me, personally I would prefer a solution which would not deassert VBUS. At least on a host only port. Honestly I don’t know how a dual role port should work.
> 
> It's been really long time since I read the OTG spec. There
> may be some diagram showing the required timeouts in the spec
> if there is one for VBUS.
> 
> Maybe we need some property to specify vbus-always-on-in-host-mode?

The MUSB otg state machine has been changed in many place since the last
time I looked at it, and I am not sure how exactly it works now.

If the $subject patch can correctly keep the VBUS on for host-only mode,
we can somehow use dr_modei value to distinguish the mode. We don't have
to create a new vbus-always-on-in-host-mode flag. VBUS has to be always
on in host-only mode anyway, until some error condition happens.

Regards,
-Bin.

Thread

[PATCH] usb-musb: keep VBUS on when device is disconnected Moreno Bartalucci <moreno.bartalucci@tecnorama.it> - 2017-03-15 15:50 +0100
  Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Bin Liu <b-liu@ti.com> - 2017-03-24 20:00 +0100
    Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Lars Melin <larsm17@gmail.com> - 2017-03-25 08:30 +0100
      Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Moreno Bartalucci <moreno.bartalucci@tecnorama.it> - 2017-03-27 15:00 +0200
        Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Bin Liu <b-liu@ti.com> - 2017-03-27 15:20 +0200
          Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Tony Lindgren <tony@atomide.com> - 2017-03-27 16:50 +0200
            Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Moreno Bartalucci <moreno.bartalucci@tecnorama.it> - 2017-03-27 18:30 +0200
              Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Tony Lindgren <tony@atomide.com> - 2017-03-27 19:20 +0200
                Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Bin Liu <b-liu@ti.com> - 2017-03-27 19:20 +0200
                Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Tony Lindgren <tony@atomide.com> - 2017-03-27 20:00 +0200
                Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Moreno Bartalucci <moreno.bartalucci@tecnorama.it> - 2017-03-28 08:20 +0200
                Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Tony Lindgren <tony@atomide.com> - 2017-03-28 17:10 +0200

csiph-web