From: Bin Liu <b-liu@ti.com>
To: Tony Lindgren <tony@atomide.com>
Cc: Moreno Bartalucci <moreno.bartalucci@tecnorama.it>,
Lars Melin <larsm17@gmail.com>,
"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Alessio Igor Bogani <abogani@kernel.org>
Subject: Re: [PATCH] usb-musb: keep VBUS on when device is disconnected
Date: Fri, 12 May 2017 10:21:44 -0500 [thread overview]
Message-ID: <20170512152144.GA651@uda0271908> (raw)
In-Reply-To: <20170512145849.GE3489@atomide.com>
On Fri, May 12, 2017 at 07:58:49AM -0700, Tony Lindgren wrote:
> * Bin Liu <b-liu@ti.com> [170512 06:43]:
> > On Thu, May 11, 2017 at 02:06:28PM -0700, Tony Lindgren wrote:
> > >
> > > Well maybe the minimal fix for now is just pretty much back to
> > > square one of this thread. This should keep VBUS always on.
> > > Then we can figure out some logic to cut VBUS later on.
> > >
> > > And yeah, the state machine is really hard to follow so some kind
> > > of clean up would be nice.
> >
> > Okay, figured out why clearing session in OTG_STATE_A_WAIT_BCON, it is
> > not for error condition handling (which is done in musb-core), but for
> > going back to b_idle state from a_host for dual-role mode. otg_timer()
> > (now is dsps_check_status()) was only called for otg port originally, so
> > it wasn't an issue, until started calling it for host mode as well when
> > runtime PM was added.
>
> OK makes sense.
>
> > > 8< -------------------
> > > --- a/drivers/usb/musb/musb_dsps.c
> > > +++ b/drivers/usb/musb/musb_dsps.c
> > > @@ -245,7 +245,6 @@ static int dsps_check_status(struct musb *musb, void *unused)
> > > dsps_mod_timer_optional(glue);
> > > break;
> > > case OTG_STATE_A_WAIT_BCON:
> > > - musb_writeb(musb->mregs, MUSB_DEVCTL, 0);
> > > skip_session = 1;
> > > /* fall */
> > >
> >
> > So the above patch breaks otg port when switching from host to device
> > mode. The following change should solve it. But Tony do you see any way
> > to improve it with glue->vbus_irq?
>
> OK. No better ideas except I think we should probably have a separate
> timer for keeping VBUS on after state changes eventually.
Currently with the patch below, VBUS is constantly on for host-only
mode, and this is what we want. Why we need a separate timer? No one
cuts VBUs now for host-only mode.
>
> I guess the real test here would be to connect a USB modem that
> changes state to the am335x-evm OTG port and make sure it works
> with commit similar to d680414d0f42 ("ARM: dts: Configure BeagleBone
> peripheral USB VBUS irq"). And also without configuring the vusb_irq.
I will test w/ and w/o vbus_irq on BeagleBone.
Moreno, would you mind to test the patch below with your modem?
Thanks,
-Bin.
>
> For the patch below, seems like the way to go for the fix assuming
> it fixes the $subject issue:
>
> Acked-by: Tony Lindgren <tony@atomide.com>
>
> > 8< --------------------
> > diff --git a/drivers/usb/musb/musb_dsps.c b/drivers/usb/musb/musb_dsps.c
> > index 9c7ee26ef388..465281244596 100644
> > --- a/drivers/usb/musb/musb_dsps.c
> > +++ b/drivers/usb/musb/musb_dsps.c
> > @@ -245,9 +245,14 @@ static int dsps_check_status(struct musb *musb, void *unused)
> > dsps_mod_timer_optional(glue);
> > break;
> > case OTG_STATE_A_WAIT_BCON:
> > + /* keep VBUS on for host-only mode */
> > + if (musb->port_mode == MUSB_PORT_MODE_HOST) {
> > + dsps_mod_timer_optional(glue);
> > + break;
> > + }
> > musb_writeb(musb->mregs, MUSB_DEVCTL, 0);
> > skip_session = 1;
> > - /* fall */
> > + /* fall through */
> >
> > case OTG_STATE_A_IDLE:
> > case OTG_STATE_B_IDLE:
next prev parent reply other threads:[~2017-05-12 15:21 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-15 14:08 [PATCH] usb-musb: keep VBUS on when device is disconnected Moreno Bartalucci
2017-03-24 18:58 ` Bin Liu
2017-03-25 7:21 ` Lars Melin
2017-03-27 12:53 ` Moreno Bartalucci
2017-03-27 13:17 ` Bin Liu
2017-03-27 14:30 ` Tony Lindgren
2017-03-27 16:20 ` Moreno Bartalucci
2017-03-27 16:59 ` Tony Lindgren
2017-03-27 17:15 ` Bin Liu
2017-03-27 17:55 ` Tony Lindgren
2017-05-11 18:50 ` Bin Liu
2017-05-11 18:55 ` Tony Lindgren
2017-05-11 19:01 ` Bin Liu
2017-05-11 19:10 ` Bin Liu
2017-05-11 19:20 ` Bin Liu
2017-05-11 19:38 ` Tony Lindgren
2017-05-11 20:02 ` Bin Liu
2017-05-11 20:23 ` Tony Lindgren
2017-05-11 20:27 ` Tony Lindgren
2017-05-11 20:44 ` Bin Liu
2017-05-11 21:06 ` Tony Lindgren
2017-05-12 13:40 ` Bin Liu
2017-05-12 14:58 ` Tony Lindgren
2017-05-12 15:21 ` Bin Liu [this message]
2017-05-12 15:43 ` Moreno Bartalucci
2017-05-12 17:21 ` Tony Lindgren
2017-05-12 17:40 ` Bin Liu
2017-05-12 17:46 ` Tony Lindgren
2017-05-15 7:07 ` Moreno Bartalucci
2017-05-15 12:24 ` Bin Liu
2017-03-28 6:10 ` Moreno Bartalucci
2017-03-28 14:59 ` Tony Lindgren
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