linux-kernel - Re: [PATCH v1] usb: typec: tcpm: Update vbus

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Message-ID: <20201211084312.GG1594451@kuha.fi.intel.com>
Date:   Fri, 11 Dec 2020 10:43:12 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Badhri Jagan Sridharan <badhri@...gle.com>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] usb: typec: tcpm: Update vbus_vsafe0v on init

On Thu, Dec 10, 2020 at 11:19:11PM -0800, Badhri Jagan Sridharan wrote:
> During init, vbus_vsafe0v does not get updated till the first
> connect as a sink. This causes TCPM to be stuck in SRC_ATTACH_WAIT
> state while booting with a sink (For instance: a headset) connected.
> 
> [    1.429168] Start toggling
> [    1.439907] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
> [    1.445242] CC1: 0 -> 0, CC2: 0 -> 0 [state TOGGLING, polarity 0, disconnected]
> [   53.358528] CC1: 0 -> 0, CC2: 0 -> 2 [state TOGGLING, polarity 0, connected]
> [   53.358564] state change TOGGLING -> SRC_ATTACH_WAIT [rev1 NONE_AMS]
> 
> Fix this by updating vbus_vsafe0v based on vbus_present status
> on boot.
> 
> Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>

One nitpick bellow, but it's so minor that you can ignore it if you
like. FWIW:

Reviewed-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>

> ---
>  drivers/usb/typec/tcpm/tcpm.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index cedc6cf82d61..58a6302c549f 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -4794,6 +4794,24 @@ static void tcpm_init(struct tcpm_port *port)
>  	if (port->vbus_present)
>  		port->vbus_never_low = true;
>  
> +	/*
> +	 * 1. When vbus_present is true, voltage on VBUS is already at VSAFE5V.
> +	 * So implicitly vbus_vsafe0v = false.
> +	 *
> +	 * 2. When vbus_present is false and TCPC does NOT support querying
> +	 * vsafe0v status, then, it's best to assume vbus is at VSAFE0V i.e.
> +	 * vbus_vsafe0v is true.
> +	 *
> +	 * 3. When vbus_present is false and TCPC does support querying vsafe0v,
> +	 * then, query tcpc for vsafe0v status.
> +	 */
> +	if (port->vbus_present)
> +		port->vbus_vsafe0v = false;
> +	else if (!port->tcpc->is_vbus_vsafe0v)
> +		port->vbus_vsafe0v = true;
> +	else
> +		port->vbus_vsafe0v = port->tcpc->is_vbus_vsafe0v(port->tcpc);

Couldn't that be the other way around?

        ...
	else if (port->tcpc->is_vbus_vsafe0v)
		port->vbus_vsafe0v = port->tcpc->is_vbus_vsafe0v(port->tcpc);
	else
		port->vbus_vsafe0v = true;
        ...

>  	tcpm_set_state(port, tcpm_default_state(port), 0);
>  
>  	if (port->tcpc->get_cc(port->tcpc, &cc1, &cc2) == 0)
> -- 
> 2.29.2.576.ga3fc446d84-goog

thanks,

-- 
heikki