* Moreno Bartalucci <moreno.bartalu...@tecnorama.it> [170327 23:12]:
> > Il giorno 27 mar 2017, alle ore 19:15, Bin Liu <b-...@ti.com> ha scritto:
> >
> > […]
> >
> > 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.
> >
>
> During my research, I used this patch to try to print the status of the usb
> port:
>
> --- a/drivers/usb/musb/musb_dsps.c 2017-03-13 09:34:31.000000000 +0100
> +++ b/drivers/usb/musb/musb_dsps.c 2017-03-13 09:36:02.000000000 +0100
> @@ -245,6 +245,8 @@ static void otg_timer(unsigned long _mus
> dev_dbg(musb->controller, "Poll devctl %02x (%s)\n", devctl,
> usb_otg_state_string(musb->xceiv->otg->state));
>
> + dev_emerg(musb->controller, "musb->xceiv->otg->state=%s,
> musb->port_mode=%d\n",
> usb_otg_state_string(musb->xceiv->otg->state),(int)musb->port_mode);
> +
> spin_lock_irqsave(&musb->lock, flags);
> switch (musb->xceiv->otg->state) {
> case OTG_STATE_A_WAIT_BCON:
>
> Unless I did something wrong, maybe it’s worth to notice that before the
> patch that apparently introduced this bug
> (2f3fd2c5bde1f94513c3dc311ae64494085ec371) I got nothing printed anywhere.
> With that patch applied, instead, I got the line printed in dmesg.
> I might be wrong but my assumption is that without that patch otg_timer was
> never called.
> If this is true, it would explain why writing 0 on DEVCTL didn’t bother
> anything: it never happened.
OK yeah that makes sense.
Thanks,
Tony
