Re: [PATCH] usb: typec: tcpm: not sink vbus if operational current is 0mA

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

Hi,

I'm sorry to keep you waiting.

On Fri, Jun 30, 2023 at 06:56:56PM +0800, Xu Yang wrote:
> PD3.0 Spec 6.4.1.3.1 said:
> For a Sink requiring no power from the Source, the Voltage (B19…10)
> Shall be set to 5V and the Operational Current Shall be set to 0mA.
> 
> Therefore, we can keep sink path closed if the operational current of
> the first fixed PDO is 0mA.
> 
> Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
> ---
>  drivers/usb/typec/tcpm/tcpm.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 829d75ebab42..4f7e4c50e847 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -4301,7 +4301,12 @@ static void run_state_machine(struct tcpm_port *port)
>  			if (port->slow_charger_loop && (current_lim > PD_P_SNK_STDBY_MW / 5))
>  				current_lim = PD_P_SNK_STDBY_MW / 5;
>  			tcpm_set_current_limit(port, current_lim, 5000);
> -			tcpm_set_charge(port, true);
> +
> +			if (pdo_max_current(port->snk_pdo[0]))
> +				tcpm_set_charge(port, true);
> +			else
> +				tcpm_log(port, "Not require power from Source");
> +
>  			if (!port->pd_supported)
>  				tcpm_set_state(port, SNK_READY, 0);
>  			else
> @@ -4582,7 +4587,10 @@ static void run_state_machine(struct tcpm_port *port)
>  			tcpm_set_current_limit(port,
>  					       tcpm_get_current_limit(port),
>  					       5000);
> -			tcpm_set_charge(port, true);
> +			if (pdo_max_current(port->snk_pdo[0]))
> +				tcpm_set_charge(port, true);
> +			else
> +				tcpm_log(port, "Not require power from Source");

Shouldn't you still always call tcpm_set_charge()?

        tcpm_set_charge(port, pdo_max_current(port->snk_pdo[0]));

I think we need to wait for comments from Guenter. I don't know this
driver well enough.

thanks,

-- 
heikki