linux-kernel - Re: [PATCH v7 3/5] phy: Add set

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Date:   Mon, 23 Jan 2017 11:58:50 -0800
From:   Stephen Boyd <stephen.boyd@...aro.org>
To:     Kishon Vijay Abraham I <kishon@...com>,
        "Peter Chen" <peter.chen@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org,
        "Andy Gross" <andy.gross@...aro.org>,
        "Bjorn Andersson" <bjorn.andersson@...aro.org>,
        "Neil Armstrong" <narmstrong@...libre.com>,
        "Arnd Bergmann" <arnd@...db.de>, "Felipe Balbi" <balbi@...nel.org>,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH v7 3/5] phy: Add set_vbus callback

Quoting Kishon Vijay Abraham I (2017-01-22 00:46:21)
> Hi,
> 
> On Saturday 21 January 2017 12:20 AM, Stephen Boyd wrote:
> > Some USB PHYs need to be told about vbus changing state
> > explicitly. For example the qcom USB HS PHY needs to toggle a bit
> > when vbus goes from low to high (VBUSVLDEXT) to cause the
> > "session valid" signal to toggle. This signal will pull up D+
> > when the phy starts running. If the vbus signal isn't routed to
> > the PHY this "session valid" signal won't ever toggle, so we have
> > to toggle it explicitly. This callback is used to do that.
> > 
> > Cc: Peter Chen <peter.chen@....com>
> > Signed-off-by: Stephen Boyd <stephen.boyd@...aro.org>
> > ---
> > 
> > New patch
> > 
> >  drivers/phy/phy-core.c  | 15 +++++++++++++++
> >  include/linux/phy/phy.h | 10 ++++++++++
> >  2 files changed, 25 insertions(+)
> > 
> > diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
> > index a268f4d6f3e9..8b1a6bfa5133 100644
> > --- a/drivers/phy/phy-core.c
> > +++ b/drivers/phy/phy-core.c
> > @@ -357,6 +357,21 @@ int phy_set_mode(struct phy *phy, enum phy_mode mode)
> >  }
> >  EXPORT_SYMBOL_GPL(phy_set_mode);
> >  
> > +int phy_set_vbus(struct phy *phy, int on)
> > +{
> > +     int ret;
> > +
> > +     if (!phy || !phy->ops->set_vbus)
> > +             return 0;
> > +
> > +     mutex_lock(&phy->mutex);
> > +     ret = phy->ops->set_vbus(phy, on);
> > +     mutex_unlock(&phy->mutex);
> > +
> > +     return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(phy_set_vbus);
> > +
> >  int phy_reset(struct phy *phy)
> >  {
> >       int ret;
> > diff --git a/include/linux/phy/phy.h b/include/linux/phy/phy.h
> > index 78bb0d7f6b11..4d1ebde7fb14 100644
> > --- a/include/linux/phy/phy.h
> > +++ b/include/linux/phy/phy.h
> > @@ -36,6 +36,7 @@ enum phy_mode {
> >   * @power_on: powering on the phy
> >   * @power_off: powering off the phy
> >   * @set_mode: set the mode of the phy
> > + * @set_vbus: enable/disable vbus in the phy (USB)
> >   * @reset: resetting the phy
> >   * @owner: the module owner containing the ops
> >   */
> > @@ -45,6 +46,7 @@ struct phy_ops {
> >       int     (*power_on)(struct phy *phy);
> >       int     (*power_off)(struct phy *phy);
> >       int     (*set_mode)(struct phy *phy, enum phy_mode mode);
> > +     int     (*set_vbus)(struct phy *phy, int on);
> 
> please avoid adding usb specific ops in generic phy ops.
> 

Is there any alternative? Something has to happen here.

The only other thing I can think of is putting back the vbus extcon in
the phy driver so it can be notified when vbus is present or not. I can
rely on phy_set_mode() being called so that we don't need to figure out
if we're in host mode or not like was being done before.