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

From Moreno Bartalucci <moreno.bartalucci@tecnorama.it>
Newsgroups linux.kernel
Subject Re: [PATCH] usb-musb: keep VBUS on when device is disconnected
Date 2017-03-27 18:30 +0200
Message-ID <tpFGO-2pv-27@gated-at.bofh.it> (permalink)
References (1 earlier) <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>
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> Il giorno 27 mar 2017, alle ore 16:30, Tony Lindgren <tony@atomide.com> ha scritto:
> 
> […]
> I wonder if the following test patch allows the mode changing
> devices to been properly found? Of course it's just for testing,
> and scanning for devices takes now 5 seconds.. But it might
> provide clues why musb thinks no devices are connected and we
> cut VBUS.
> 
> […]

Hi Tony,

thanks for your patch.

I tested it with both current mainline kernel and my “production” kernel (4.9.13): they have the same behaviour.

During boot, vbus is first asserted, then removed for a slightly longer time than before (most likely 5 seconds now), then reasserted.

When my device is mode-switched, it is working properly with your patch.

If I understood your patch, however, if the device (anyone, not just my one) takes longer to switch, VBUS is deasserted anyway.

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.

Regards,

Moreno

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[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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