* Bin Liu <b-liu@xxxxxx> [170327 10:17]: > On Mon, Mar 27, 2017 at 09:59:47AM -0700, Tony Lindgren wrote: > > * Moreno Bartalucci <moreno.bartalucci@xxxxxxxxxxxx> [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. Yup.. I looked up the timers in the OTG spec and they are described in chapter "8.5.5.2" as a_wait_bcon_tmo or a_wait_bcon_tmr. But I could not find any values for them. Anyways, clearly we want things working with real devices :) > 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. Yeh and it seems PM still works with the $subject patch also for host mode. So maybe that's enough to fix the issue. Also I don't have any idea why for ages we have been writing 0 to devctl there.. Maybe we've had a bug there that only now shows up when we idle things. Anyways, for the $subject patch related to MUSB runtime PM: Tested-by: Tony Lindgren <tony@xxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
