From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757598AbdELPV7 (ORCPT ); Fri, 12 May 2017 11:21:59 -0400 Received: from fllnx210.ext.ti.com ([198.47.19.17]:24028 "EHLO fllnx210.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754913AbdELPV4 (ORCPT ); Fri, 12 May 2017 11:21:56 -0400 Date: Fri, 12 May 2017 10:21:44 -0500 From: Bin Liu To: Tony Lindgren CC: Moreno Bartalucci , Lars Melin , "linux-omap@vger.kernel.org" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Alessio Igor Bogani Subject: Re: [PATCH] usb-musb: keep VBUS on when device is disconnected Message-ID: <20170512152144.GA651@uda0271908> Mail-Followup-To: Bin Liu , Tony Lindgren , Moreno Bartalucci , Lars Melin , "linux-omap@vger.kernel.org" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Alessio Igor Bogani References: <20170511190100.GF7154@uda0271908> <20170511191005.GG7154@uda0271908> <20170511192013.GA4459@uda0271908> <20170511193810.GX3489@atomide.com> <20170511200220.GH7154@uda0271908> <20170511202306.GY3489@atomide.com> <20170511204406.GI7154@uda0271908> <20170511210628.GA3489@atomide.com> <20170512134042.GK7154@uda0271908> <20170512145849.GE3489@atomide.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20170512145849.GE3489@atomide.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 12, 2017 at 07:58:49AM -0700, Tony Lindgren wrote: > * Bin Liu [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 > > > 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: