Re: [PATCH] usb: typec: tcpm: Fix SINK_DISCOVERY current limit for Rp-default

[Heikki Krogerus]

On Mon, May 10, 2021 at 02:17:56PM -0700, Badhri Jagan Sridharan wrote:
> This is a regression introduced by
> <1373fefc6243cc96b3565f0ffffadfac4ccfb977>
> "Allow slow charging loops to comply to pSnkStby".
> 
> When Source advertises Rp-default, tcpm would request 500mA when in
> SINK_DISCOVERY, Type-C spec advises the sink to follow BC1.2 current
> limits when Rp-default is advertised.
> [12750.503381] Requesting mux state 1, usb-role 2, orientation 1
> [12750.503837] state change SNK_ATTACHED -> SNK_STARTUP [rev3 NONE_AMS]
> [12751.003891] state change SNK_STARTUP -> SNK_DISCOVERY
> [12751.003900] Setting voltage/current limit 5000 mV 500 mA
> 
> This patch restores the behavior where the tcpm would request 0mA when
> Rp-default is advertised by the source.
> [   73.174252] Requesting mux state 1, usb-role 2, orientation 1
> [   73.174749] state change SNK_ATTACHED -> SNK_STARTUP [rev3 NONE_AMS]
> [   73.674800] state change SNK_STARTUP -> SNK_DISCOVERY
> [   73.674808] Setting voltage/current limit 5000 mV 0 mA
> 
> During SNK_DISCOVERY, Cap the current limit to PD_P_SNK_STDBY_MW / 5 only
> for slow_charger_loop case.
> 
> Fixes: 1373fefc6243 ("Allow slow charging loops to comply to pSnkStby")
> Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx>

Acked-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>

> ---
>  drivers/usb/typec/tcpm/tcpm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index c4fdc00a3bc8..a73299a08ef7 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -4055,7 +4055,7 @@ static void run_state_machine(struct tcpm_port *port)
>  		if (port->vbus_present) {
>  			u32 current_lim = tcpm_get_current_limit(port);
>  
> -			if (port->slow_charger_loop || (current_lim > PD_P_SNK_STDBY_MW / 5))
> +			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);
> -- 
> 2.31.1.607.g51e8a6a459-goog

-- 
heikki