Messages in this thread | | | Date | Mon, 27 Mar 2017 12:15:34 -0500 | From | Bin Liu <> | Subject | Re: [PATCH] usb-musb: keep VBUS on when device is disconnected |
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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.
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