linux-kernel - Re: [PATCH 2/3] [PATCH v2 2/3] usb: typec: tcpm: Do not disconnect link for self powered devices

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Message-ID: <CAPTae5LODDhhHDL2Dq6L12sSqT4-KNaELtZNy++g_4B=wb7QsQ@mail.gmail.com>
Date:   Mon, 1 Oct 2018 12:45:49 -0700
From:   Badhri Jagan Sridharan <badhri@...gle.com>
To:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     robh+dt@...nel.org, mark.rutland@....com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        cw00.choi@...sung.com, a.hajda@...sung.com, jun.li@....com,
        Guenter Roeck <linux@...ck-us.net>, devicetree@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        USB <linux-usb@...r.kernel.org>
Subject: Re: [PATCH 2/3] [PATCH v2 2/3] usb: typec: tcpm: Do not disconnect
 link for self powered devices

Sure. Just resent the patch stack !
On Mon, Oct 1, 2018 at 2:54 AM Heikki Krogerus
<heikki.krogerus@...ux.intel.com> wrote:
>
> On Fri, Sep 28, 2018 at 04:47:02PM -0700, Badhri Jagan Sridharan wrote:
> > During HARD_RESET the data link is disconnected.
> > For self powered device, the spec is advising against doing that.
> >
> > >From USB_PD_R3_0
> > 7.1.5 Response to Hard Resets
> > Device operation during and after a Hard Reset is defined as follows:
> > Self-powered devices Should Not disconnect from USB during a Hard Reset
> > (see Section 9.1.2).
> > Bus powered devices will disconnect from USB during a Hard Reset due to the
> > loss of their power source.
> >
> > Tackle this by letting TCPM know whether the device is self or bus powered.
> >
> > This overcomes unnecessary port disconnections from hard reset.
> > Also, speeds up the enumeration time when connected to Type-A ports.
> >
> > Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>
>
> Could you rebase these on top of the latest usb-next. These are not
> going to apply cleanly on top of it because tcpm.c and all port
> drivers are now in their own directory drivers/usb/typec/tcpm/.
>
> Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
>
> > ---------
> > Version history:
> >
> > V2:
> > Based on feedback from heikki.krogerus@...ux.intel.com
> > - self_powered added to the struct tcpm_port which is populated from
> >   a. "connector" node of the device tree in tcpm_fw_get_caps()
> >   b. "self_powered" node of the tcpc_config in tcpm_copy_caps
> >
> > Based on feedbase from linux@...ck-us.net
> > - Code was refactored
> > - SRC_HARD_RESET_VBUS_OFF sets the link state to false based
> >   on self_powered flag
> >
> > V1 located here:
> > https://lkml.org/lkml/2018/9/13/94
> > ---
> >  drivers/usb/typec/tcpm.c | 12 ++++++++++--
> >  include/linux/usb/tcpm.h |  1 +
> >  2 files changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/usb/typec/tcpm.c b/drivers/usb/typec/tcpm.c
> > index 4f1f4215f3d6e..c3ac0e46106b4 100644
> > --- a/drivers/usb/typec/tcpm.c
> > +++ b/drivers/usb/typec/tcpm.c
> > @@ -317,6 +317,9 @@ struct tcpm_port {
> >       /* Deadline in jiffies to exit src_try_wait state */
> >       unsigned long max_wait;
> >
> > +     /* port belongs to a self powered device */
> > +     bool self_powered;
> > +
> >  #ifdef CONFIG_DEBUG_FS
> >       struct dentry *dentry;
> >       struct mutex logbuffer_lock;    /* log buffer access lock */
> > @@ -3257,7 +3260,8 @@ static void run_state_machine(struct tcpm_port *port)
> >       case SRC_HARD_RESET_VBUS_OFF:
> >               tcpm_set_vconn(port, true);
> >               tcpm_set_vbus(port, false);
> > -             tcpm_set_roles(port, false, TYPEC_SOURCE, TYPEC_HOST);
> > +             tcpm_set_roles(port, port->self_powered, TYPEC_SOURCE,
> > +                            TYPEC_HOST);
> >               tcpm_set_state(port, SRC_HARD_RESET_VBUS_ON, PD_T_SRC_RECOVER);
> >               break;
> >       case SRC_HARD_RESET_VBUS_ON:
> > @@ -3270,7 +3274,8 @@ static void run_state_machine(struct tcpm_port *port)
> >               memset(&port->pps_data, 0, sizeof(port->pps_data));
> >               tcpm_set_vconn(port, false);
> >               tcpm_set_charge(port, false);
> > -             tcpm_set_roles(port, false, TYPEC_SINK, TYPEC_DEVICE);
> > +             tcpm_set_roles(port, port->self_powered, TYPEC_SINK,
> > +                            TYPEC_DEVICE);
> >               /*
> >                * VBUS may or may not toggle, depending on the adapter.
> >                * If it doesn't toggle, transition to SNK_HARD_RESET_SINK_ON
> > @@ -4409,6 +4414,8 @@ static int tcpm_fw_get_caps(struct tcpm_port *port,
> >               return -EINVAL;
> >       port->operating_snk_mw = mw / 1000;
> >
> > +     port->self_powered = fwnode_property_read_bool(fwnode, "self-powered");
> > +
> >       return 0;
> >  }
> >
> > @@ -4717,6 +4724,7 @@ static int tcpm_copy_caps(struct tcpm_port *port,
> >       port->typec_caps.prefer_role = tcfg->default_role;
> >       port->typec_caps.type = tcfg->type;
> >       port->typec_caps.data = tcfg->data;
> > +     port->self_powered = port->tcpc->config->self_powered;
> >
> >       return 0;
> >  }
> > diff --git a/include/linux/usb/tcpm.h b/include/linux/usb/tcpm.h
> > index 7e7fbfb84e8e3..50c74a77db55c 100644
> > --- a/include/linux/usb/tcpm.h
> > +++ b/include/linux/usb/tcpm.h
> > @@ -89,6 +89,7 @@ struct tcpc_config {
> >       enum typec_port_data data;
> >       enum typec_role default_role;
> >       bool try_role_hw;       /* try.{src,snk} implemented in hardware */
> > +     bool self_powered;      /* port belongs to a self powered device */
> >
> >       const struct typec_altmode_desc *alt_modes;
> >  };
>
> Thanks,
>
> --
> heikki