Hi,
I'm sorry, but I did not understand the subject line?
On Thu, Jan 06, 2022 at 04:53:25PM +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@xxxxxxxxxxxxxxx>
> Signed-off-by: Xu Yang <xu.yang_2@xxxxxxx>
Okay, the commit message does explain what's this about, but could you
still change the subject to "..don't touch the CC line if it's VCONN
source" or something like that?
> ---
> 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) {
Isn't that bit optional? tcpm.c already knows the vconn status, right?
If it does, then maybe it would be safer to change the API so that you
pass also the information about the vconn status to the .set_cc
callback? So in this case:
static int tcpci_set_cc(struct tpcp_dev *tcpc, enum typec_cc_status cc, enum typec_role vconn)
That way the support would also be for all the other drivers too, so
not just for tcpci.c.
> + 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
