Messages in this thread Patch in this message | | | Subject | Re: [PATCH] usb-musb: keep VBUS on when device is disconnected | From | Moreno Bartalucci <> | Date | Tue, 28 Mar 2017 08:10:00 +0200 |
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> Il giorno 27 mar 2017, alle ore 19:15, Bin Liu <b-liu@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.
Regards,
Moreno
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