linux-kernel - Re: [PATCH v6 03/14] usb: typec: tcpci: update ROLE

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Message-ID: <20200915121216.GD1139641@kuha.fi.intel.com>
Date:   Tue, 15 Sep 2020 15:12:16 +0300
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 v6 03/14] usb: typec: tcpci: update ROLE_CONTROL for DRP

On Mon, Aug 31, 2020 at 07:59:16PM -0700, Badhri Jagan Sridharan wrote:
> ROLE_CONTROL register would not have the actual CC terminations
> unless the port does not set ROLE_CONTROL.DRP. For DRP ports,
> CC_STATUS.cc1/cc2 indicates the final terminations applied
> when TCPC enters potential_connect_as_source/_sink.
> For DRP ports, infer port role from CC_STATUS and set corresponding
> CC terminations before setting the orientation.
> 
> Signed-off-by: Badhri Jagan Sridharan <badhri@...gle.com>

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

> ---
> Changes since v1:
>  - Changing patch version to v6 to fix version number confusion.
> ---
>  drivers/usb/typec/tcpm/tcpci.c | 37 +++++++++++++++++++++++++++++++++-
>  1 file changed, 36 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> index 7d36d5e2d3f7..7d9491ba62fb 100644
> --- a/drivers/usb/typec/tcpm/tcpci.c
> +++ b/drivers/usb/typec/tcpm/tcpci.c
> @@ -191,12 +191,47 @@ static int tcpci_set_polarity(struct tcpc_dev *tcpc,
>  	struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
>  	unsigned int reg;
>  	int ret;
> +	enum typec_cc_status cc1, cc2;
>  
> -	/* Keep the disconnect cc line open */
> +	/* Obtain Rp setting from role control */
>  	ret = regmap_read(tcpci->regmap, TCPC_ROLE_CTRL, &reg);
>  	if (ret < 0)
>  		return ret;
>  
> +	ret = tcpci_get_cc(tcpc, &cc1, &cc2);
> +	if (ret < 0)
> +		return ret;
> +
> +	/*
> +	 * When port has drp toggling enabled, ROLE_CONTROL would only have the initial
> +	 * terminations for the toggling and does not indicate the final cc
> +	 * terminations when ConnectionResult is 0 i.e. drp toggling stops and
> +	 * the connection is resolbed. Infer port role from TCPC_CC_STATUS based on the
> +	 * terminations seen. The port role is then used to set the cc terminations.
> +	 */
> +	if (reg & TCPC_ROLE_CTRL_DRP) {
> +		/* Disable DRP for the OPEN setting to take effect */
> +		reg = reg & ~TCPC_ROLE_CTRL_DRP;
> +
> +		if (polarity == TYPEC_POLARITY_CC2) {
> +			reg &= ~(TCPC_ROLE_CTRL_CC2_MASK << TCPC_ROLE_CTRL_CC2_SHIFT);
> +			/* Local port is source */
> +			if (cc2 == TYPEC_CC_RD)
> +				/* Role control would have the Rp setting when DRP was enabled */
> +				reg |= TCPC_ROLE_CTRL_CC_RP << TCPC_ROLE_CTRL_CC2_SHIFT;
> +			else
> +				reg |= TCPC_ROLE_CTRL_CC_RD << TCPC_ROLE_CTRL_CC2_SHIFT;
> +		} else {
> +			reg &= ~(TCPC_ROLE_CTRL_CC1_MASK << TCPC_ROLE_CTRL_CC1_SHIFT);
> +			/* Local port is source */
> +			if (cc1 == TYPEC_CC_RD)
> +				/* Role control would have the Rp setting when DRP was enabled */
> +				reg |= TCPC_ROLE_CTRL_CC_RP << TCPC_ROLE_CTRL_CC1_SHIFT;
> +			else
> +				reg |= TCPC_ROLE_CTRL_CC_RD << TCPC_ROLE_CTRL_CC1_SHIFT;
> +		}
> +	}
> +
>  	if (polarity == TYPEC_POLARITY_CC2)
>  		reg |= TCPC_ROLE_CTRL_CC_OPEN << TCPC_ROLE_CTRL_CC1_SHIFT;
>  	else
> -- 
> 2.28.0.402.g5ffc5be6b7-goog

-- 
heikki