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From: Bin Liu <b-liu@ti.com>
To: Tony Lindgren <tony@atomide.com>
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>
Subject: Re: [PATCH] usb-musb: keep VBUS on when device is disconnected
Date: Mon, 27 Mar 2017 12:15:34 -0500	[thread overview]
Message-ID: <20170327171534.GA4403@uda0271908> (raw)
In-Reply-To: <20170327165946.GL10760@atomide.com>

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.

  reply	other threads:[~2017-03-27 17:17 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-15 14:08 [PATCH] usb-musb: keep VBUS on when device is disconnected Moreno Bartalucci
2017-03-24 18:58 ` Bin Liu
2017-03-25  7:21   ` Lars Melin
2017-03-27 12:53     ` Moreno Bartalucci
2017-03-27 13:17       ` Bin Liu
2017-03-27 14:30         ` Tony Lindgren
2017-03-27 16:20           ` Moreno Bartalucci
2017-03-27 16:59             ` Tony Lindgren
2017-03-27 17:15               ` Bin Liu [this message]
2017-03-27 17:55                 ` Tony Lindgren
2017-05-11 18:50                   ` Bin Liu
2017-05-11 18:55                     ` Tony Lindgren
2017-05-11 19:01                       ` Bin Liu
2017-05-11 19:10                         ` Bin Liu
2017-05-11 19:20                           ` Bin Liu
2017-05-11 19:38                             ` Tony Lindgren
2017-05-11 20:02                               ` Bin Liu
2017-05-11 20:23                                 ` Tony Lindgren
2017-05-11 20:27                                   ` Tony Lindgren
2017-05-11 20:44                                   ` Bin Liu
2017-05-11 21:06                                     ` Tony Lindgren
2017-05-12 13:40                                       ` Bin Liu
2017-05-12 14:58                                         ` Tony Lindgren
2017-05-12 15:21                                           ` Bin Liu
2017-05-12 15:43                                             ` Moreno Bartalucci
2017-05-12 17:21                                             ` Tony Lindgren
2017-05-12 17:40                                               ` Bin Liu
2017-05-12 17:46                                                 ` Tony Lindgren
2017-05-15  7:07                                             ` Moreno Bartalucci
2017-05-15 12:24                                               ` Bin Liu
2017-03-28  6:10                 ` Moreno Bartalucci
2017-03-28 14:59                   ` Tony Lindgren

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