From: Heikki Krogerus <heikki.krogerus@linux.intel.com>
To: Xu Yang <xu.yang_2@nxp.com>
Cc: linux@roeck-us.net, gregkh@linuxfoundation.org,
linux-usb@vger.kernel.org, jun.li@nxp.com, linux-imx@nxp.com
Subject: Re: [PATCH v2] usb: typec: tcpci: don't touch CC line if it's Vconn source
Date: Wed, 12 Jan 2022 13:04:20 +0200 [thread overview]
Message-ID: <Yd61tEZZfnYU/L1V@kuha.fi.intel.com> (raw)
In-Reply-To: <20220112094116.616272-1-xu.yang_2@nxp.com>
On Wed, Jan 12, 2022 at 05:41:16PM +0800, Xu Yang wrote:
> With the AMS and Collision Avoidance, tcpm often needs to change the CC's
> termination. When one CC line is souring Vconn, if we still change its
> termination, the voltage of the another CC line is likely to be fluctuant
> and unstable.
>
> Therefore, we should verify whether a CC line is soucing Vconn before
> changing its termination. And only changing the termination that is
> not a Vconn line. This can be done by reading the VCONN Present bit of
> POWER_ STATUS register. To determinate the polarity, we can read the
> Plug Orientation bit of TCPC_CONTROL register. Since only if Plug
> Orientation is set, Vconn can be sourced.
>
> Fixes: 0908c5aca31e ("usb: typec: tcpm: AMS and Collision Avoidance")
> cc: <stable@vger.kernel.org>
> Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> ---
> v2: changed subject line
> ---
> drivers/usb/typec/tcpm/tcpci.c | 27 +++++++++++++++++++++++++++
> drivers/usb/typec/tcpm/tcpci.h | 1 +
> 2 files changed, 28 insertions(+)
>
> diff --git a/drivers/usb/typec/tcpm/tcpci.c b/drivers/usb/typec/tcpm/tcpci.c
> index 35a1307349a2..0bf4cbfaa21c 100644
> --- a/drivers/usb/typec/tcpm/tcpci.c
> +++ b/drivers/usb/typec/tcpm/tcpci.c
> @@ -75,9 +75,26 @@ static int tcpci_write16(struct tcpci *tcpci, unsigned int reg, u16 val)
> static int tcpci_set_cc(struct tcpc_dev *tcpc, enum typec_cc_status cc)
> {
> struct tcpci *tcpci = tcpc_to_tcpci(tcpc);
> + bool vconn_pres = false;
> + enum typec_cc_polarity polarity = TYPEC_POLARITY_CC1;
> unsigned int reg;
> int ret;
>
> + ret = regmap_read(tcpci->regmap, TCPC_POWER_STATUS, ®);
> + if (ret < 0)
> + return ret;
> +
> + if (reg & TCPC_POWER_STATUS_VCONN_PRES) {
> + vconn_pres = true;
> +
> + ret = regmap_read(tcpci->regmap, TCPC_TCPC_CTRL, ®);
> + if (ret < 0)
> + return ret;
> +
> + if (reg & TCPC_TCPC_CTRL_ORIENTATION)
> + polarity = TYPEC_POLARITY_CC2;
> + }
> +
> switch (cc) {
> case TYPEC_CC_RA:
> reg = (TCPC_ROLE_CTRL_CC_RA << TCPC_ROLE_CTRL_CC1_SHIFT) |
> @@ -112,6 +129,16 @@ static int tcpci_set_cc(struct tcpc_dev *tcpc, enum typec_cc_status cc)
> break;
> }
>
> + if (vconn_pres) {
> + if (polarity == TYPEC_POLARITY_CC2) {
> + reg &= ~(TCPC_ROLE_CTRL_CC1_MASK << TCPC_ROLE_CTRL_CC1_SHIFT);
> + reg |= (TCPC_ROLE_CTRL_CC_OPEN << TCPC_ROLE_CTRL_CC1_SHIFT);
> + } else {
> + reg &= ~(TCPC_ROLE_CTRL_CC2_MASK << TCPC_ROLE_CTRL_CC2_SHIFT);
> + reg |= (TCPC_ROLE_CTRL_CC_OPEN << TCPC_ROLE_CTRL_CC2_SHIFT);
> + }
> + }
> +
> ret = regmap_write(tcpci->regmap, TCPC_ROLE_CTRL, reg);
> if (ret < 0)
> return ret;
> diff --git a/drivers/usb/typec/tcpm/tcpci.h b/drivers/usb/typec/tcpm/tcpci.h
> index 2be7a77d400e..b2edd45f13c6 100644
> --- a/drivers/usb/typec/tcpm/tcpci.h
> +++ b/drivers/usb/typec/tcpm/tcpci.h
> @@ -98,6 +98,7 @@
> #define TCPC_POWER_STATUS_SOURCING_VBUS BIT(4)
> #define TCPC_POWER_STATUS_VBUS_DET BIT(3)
> #define TCPC_POWER_STATUS_VBUS_PRES BIT(2)
> +#define TCPC_POWER_STATUS_VCONN_PRES BIT(1)
> #define TCPC_POWER_STATUS_SINKING_VBUS BIT(0)
>
> #define TCPC_FAULT_STATUS 0x1f
> --
> 2.25.1
--
heikki
next prev parent reply other threads:[~2022-01-12 11:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-12 9:41 [PATCH v2] usb: typec: tcpci: don't touch CC line if it's Vconn source Xu Yang
2022-01-12 11:04 ` Heikki Krogerus [this message]
2022-01-12 16:00 ` Guenter Roeck
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