Re: [PATCH] usb: typec: tcpm: reset hard_reset_count for any disconnect

[Guenter Roeck <linux@roeck-us.net>]

On Mon, Oct 12, 2020 at 07:03:12PM +0800, Li Jun wrote:
> Current tcpm_detach() only reset hard_reset_count if port->attached
> is true, this may cause this counter clear is missed if the CC
> disconnect event is generated after tcpm_port_reset() is done
> by other events, e.g. VBUS off comes first before CC disconect for
> a power sink, in that case the first tcpm_detach() will only clear
> port->attached flag but leave hard_reset_count there because
> tcpm_port_is_disconnected() is still false, then later tcpm_detach()
> by CC disconnect will directly return due to port->attached is cleared,
> finally this will result tcpm will not try hard reset or error recovery
> for later attach.
> 
> ChiYuan reported this issue on his platform with below tcpm trace:
> After power sink session setup after hard reset 2 times, detach
> from the power source and then attach:
> [ 4848.046358] VBUS off
> [ 4848.046384] state change SNK_READY -> SNK_UNATTACHED
> [ 4848.050908] Setting voltage/current limit 0 mV 0 mA
> [ 4848.050936] polarity 0
> [ 4848.052593] Requesting mux state 0, usb-role 0, orientation 0
> [ 4848.053222] Start toggling
> [ 4848.086500] state change SNK_UNATTACHED -> TOGGLING
> [ 4848.089983] CC1: 0 -> 0, CC2: 3 -> 3 [state TOGGLING, polarity 0, connected]
> [ 4848.089993] state change TOGGLING -> SNK_ATTACH_WAIT
> [ 4848.090031] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @200 ms
> [ 4848.141162] CC1: 0 -> 0, CC2: 3 -> 0 [state SNK_ATTACH_WAIT, polarity 0, disconnected]
> [ 4848.141170] state change SNK_ATTACH_WAIT -> SNK_ATTACH_WAIT
> [ 4848.141184] pending state change SNK_ATTACH_WAIT -> SNK_UNATTACHED @20 ms
> [ 4848.163156] state change SNK_ATTACH_WAIT -> SNK_UNATTACHED [delayed 20 ms]
> [ 4848.163162] Start toggling
> [ 4848.216918] CC1: 0 -> 0, CC2: 0 -> 3 [state TOGGLING, polarity 0, connected]
> [ 4848.216954] state change TOGGLING -> SNK_ATTACH_WAIT
> [ 4848.217080] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @200 ms
> [ 4848.231771] CC1: 0 -> 0, CC2: 3 -> 0 [state SNK_ATTACH_WAIT, polarity 0, disconnected]
> [ 4848.231800] state change SNK_ATTACH_WAIT -> SNK_ATTACH_WAIT
> [ 4848.231857] pending state change SNK_ATTACH_WAIT -> SNK_UNATTACHED @20 ms
> [ 4848.256022] state change SNK_ATTACH_WAIT -> SNK_UNATTACHED [delayed20 ms]
> [ 4848.256049] Start toggling
> [ 4848.871148] VBUS on
> [ 4848.885324] CC1: 0 -> 0, CC2: 0 -> 3 [state TOGGLING, polarity 0, connected]
> [ 4848.885372] state change TOGGLING -> SNK_ATTACH_WAIT
> [ 4848.885548] pending state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED @200 ms
> [ 4849.088240] state change SNK_ATTACH_WAIT -> SNK_DEBOUNCED [delayed200 ms]
> [ 4849.088284] state change SNK_DEBOUNCED -> SNK_ATTACHED
> [ 4849.088291] polarity 1
> [ 4849.088769] Requesting mux state 1, usb-role 2, orientation 2
> [ 4849.088895] state change SNK_ATTACHED -> SNK_STARTUP
> [ 4849.088907] state change SNK_STARTUP -> SNK_DISCOVERY
> [ 4849.088915] Setting voltage/current limit 5000 mV 0 mA
> [ 4849.088927] vbus=0 charge:=1
> [ 4849.090505] state change SNK_DISCOVERY -> SNK_WAIT_CAPABILITIES
> [ 4849.090828] pending state change SNK_WAIT_CAPABILITIES -> SNK_READY @240 ms
> [ 4849.335878] state change SNK_WAIT_CAPABILITIES -> SNK_READY [delayed240 ms]
> 
> this patch fix this issue by clear hard_reset_count at any cases
> of cc disconnect, í.e. don't check port->attached flag.
> 
> Cc: stable@vger.kernel.org
> Fixes: 4b4e02c83167 ("typec: tcpm: Move out of staging")
> Reported-and-tested-by: ChiYuan Huang <cy_huang@richtek.com>
> Signed-off-by: Li Jun <jun.li@nxp.com>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>  drivers/usb/typec/tcpm/tcpm.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
> index 55535c4..a6fae1f 100644
> --- a/drivers/usb/typec/tcpm/tcpm.c
> +++ b/drivers/usb/typec/tcpm/tcpm.c
> @@ -2890,6 +2890,9 @@ static void tcpm_reset_port(struct tcpm_port *port)
>  
>  static void tcpm_detach(struct tcpm_port *port)
>  {
> +	if (tcpm_port_is_disconnected(port))
> +		port->hard_reset_count = 0;
> +
>  	if (!port->attached)
>  		return;
>  
> @@ -2898,9 +2901,6 @@ static void tcpm_detach(struct tcpm_port *port)
>  		port->tcpc->set_bist_data(port->tcpc, false);
>  	}
>  
> -	if (tcpm_port_is_disconnected(port))
> -		port->hard_reset_count = 0;
> -
>  	tcpm_reset_port(port);
>  }
>  
> -- 
> 2.7.4
>