Re: [PATCH v6 11/25] usb: chipidea: vbus event may exist before starting gadget

From: Peter Chen <hzpeterchen@gmail.com>
To: Stephen Boyd <stephen.boyd@linaro.org>
Cc: linux-usb@vger.kernel.org, Peter Chen <peter.chen@nxp.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Neil Armstrong <narmstrong@baylibre.com>,
	linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Andy Gross <andy.gross@linaro.org>,
	linux-arm-kernel@lists.infradead.org,
	Felipe Balbi <balbi@kernel.org>
Subject: Re: [PATCH v6 11/25] usb: chipidea: vbus event may exist before starting gadget
Date: Thu, 12 Jan 2017 17:52:20 +0800	[thread overview]
Message-ID: <20170112095220.GB15726@b29397-desktop> (raw)
In-Reply-To: <148418115431.32258.10648057913784071156@sboyd-linaro>

On Wed, Jan 11, 2017 at 04:32:34PM -0800, Stephen Boyd wrote:
> Quoting Peter Chen (2017-01-03 00:00:31)
> > On Wed, Dec 28, 2016 at 02:56:57PM -0800, Stephen Boyd wrote:
> > > From: Peter Chen <peter.chen@nxp.com>
> > > 
> > > At some situations, the vbus may already be there before starting
> > > gadget. So we need to check vbus event after switch to gadget in
> > > order to handle missing vbus event. The typical use cases are plugging
> > > vbus cable before driver load or the vbus has already been there
> > > after stopping host but before starting gadget.
> > > 
> > > Signed-off-by: Peter Chen <peter.chen@nxp.com>
> > > Tested-by: Stephen Boyd <stephen.boyd@linaro.org>
> > > Reviewed-by: Stephen Boyd <stephen.boyd@linaro.org>
> > > [sboyd@codeaurora.org: Modify comment text per list discussion]
> > > Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
> > > ---
> > >  drivers/usb/chipidea/core.c |  4 ----
> > >  drivers/usb/chipidea/otg.c  | 14 +++++++++-----
> > >  drivers/usb/chipidea/udc.c  |  2 ++
> > >  3 files changed, 11 insertions(+), 9 deletions(-)
> > > 
> > > diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
> > > index 8a020ebbbe2f..37f888e31f10 100644
> > > --- a/drivers/usb/chipidea/core.c
> > > +++ b/drivers/usb/chipidea/core.c
> > > @@ -979,10 +979,6 @@ static int ci_hdrc_probe(struct platform_device *pdev)
> > >       }
> > >  
> > >       if (!ci_otg_is_fsm_mode(ci)) {
> > > -             /* only update vbus status for peripheral */
> > > -             if (ci->role == CI_ROLE_GADGET)
> > > -                     ci_handle_vbus_change(ci);
> > > -
> > >               ret = ci_role_start(ci, ci->role);
> > >               if (ret) {
> > >                       dev_err(dev, "can't start %s role\n",
> > > diff --git a/drivers/usb/chipidea/otg.c b/drivers/usb/chipidea/otg.c
> > > index 695f3fe3ae21..c972ed23b8ec 100644
> > > --- a/drivers/usb/chipidea/otg.c
> > > +++ b/drivers/usb/chipidea/otg.c
> > > @@ -134,9 +134,9 @@ void ci_handle_vbus_change(struct ci_hdrc *ci)
> > >       if (!ci->is_otg)
> > >               return;
> > >  
> > > -     if (hw_read_otgsc(ci, OTGSC_BSV))
> > > +     if (hw_read_otgsc(ci, OTGSC_BSV) && !ci->vbus_active)
> > >               usb_gadget_vbus_connect(&ci->gadget);
> > > -     else
> > > +     else if (!hw_read_otgsc(ci, OTGSC_BSV) && ci->vbus_active)
> > >               usb_gadget_vbus_disconnect(&ci->gadget);
> > >  }
> > >  
> > > @@ -175,10 +175,14 @@ static void ci_handle_id_switch(struct ci_hdrc *ci)
> > >  
> > >               ci_role_stop(ci);
> > >  
> > > -             if (role == CI_ROLE_GADGET)
> > > +             if (role == CI_ROLE_GADGET &&
> > > +                             IS_ERR(ci->platdata->vbus_extcon.edev))
> > >                       /*
> > > -                      * wait vbus lower than OTGSC_BSV before connecting
> > > -                      * to host
> > > +                      * wait vbus lower than OTGSC_BSV before connecting to
> > > +                      * host. If connecting status is from an external
> > > +                      * connector instead of register, we don't need to care
> > > +                      * vbus on the board, since it will not affect external
> > > +                      * connector status.
> > >                        */
> > >                       hw_wait_vbus_lower_bsv(ci);
> > >  
> > > diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> > > index 732b281485de..0db56fb7e9e9 100644
> > > --- a/drivers/usb/chipidea/udc.c
> > > +++ b/drivers/usb/chipidea/udc.c
> > > @@ -1961,6 +1961,8 @@ static int udc_id_switch_for_device(struct ci_hdrc *ci)
> > >               /* Clear and enable BSV irq */
> > >               hw_write_otgsc(ci, OTGSC_BSVIS | OTGSC_BSVIE,
> > >                                       OTGSC_BSVIS | OTGSC_BSVIE);
> > > +     /* vbus change may has already been occurred */
> > > +     ci_handle_vbus_change(ci);
> > >  
> > >       return 0;
> > 
> > After thinking more, the above change will affect OTG FSM which calls
> > this API too, but handle vbus change later, see ci_otg_start_host and
> > ci_otg_start_gadget. How about changing patch like below:
> 
> Ok. I'll give it a spin but I think that should work too. I don't have
> any hardware to test the OTG FSM to make sure things don't break.

ci_handle_id_switch is only called at non OTG FSM mode, so it will not
affect OTG FSM.

-- 

Best Regards,
Peter Chen