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

From	Bin Liu <b-liu@ti.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] usb-musb: keep VBUS on when device is disconnected
Date	2017-03-27 19:20 +0200
Message-ID	<tpGtc-34b-17@gated-at.bofh.it> (permalink)
References	(3 earlier) <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>
Organization	linux.* mail to news gateway

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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

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