Guenter Roeck <linux@xxxxxxxxxxxx> 於 2020年9月5日 週六 上午3:41寫道： > > On 9/3/20 9:21 AM, ChiYuan Huang wrote: > > Guenter Roeck <linux@xxxxxxxxxxxx> 於 2020年9月3日 週四 上午12:57寫道： > >> > >> On Wed, Sep 02, 2020 at 11:35:33PM +0800, cy_huang wrote: > >>> From: ChiYuan Huang <cy_huang@xxxxxxxxxxx> > >>> > >>> Fix: If vbus event is before cc_event trigger, hard_reset_count > >>> won't bt reset for some case. > >>> > >>> Signed-off-by: ChiYuan Huang <cy_huang@xxxxxxxxxxx> > >>> --- > >>> Below's the flow. > >>> > >>> _tcpm_pd_vbus_off() -> run_state_machine to change state to SNK_UNATTACHED > >>> call tcpm_snk_detach() -> tcpm_snk_detach() -> tcpm_detach() > >>> tcpm_port_is_disconnected() will be called. > >>> But port->attached is still true and port->cc1=open and port->cc2=open > >>> > >>> It cause tcpm_port_is_disconnected return false, then hard_reset_count won't be reset. > >>> After that, tcpm_reset_port() is called. > >>> port->attached become false. > >>> > >>> After that, cc now trigger cc_change event, the hard_reset_count will be kept. > >>> Even tcpm_detach will be called, due to port->attached is false, tcpm_detach() > >>> will directly return. > >>> > >>> CC_EVENT will only trigger drp toggling again. > >>> --- > >>> drivers/usb/typec/tcpm/tcpm.c | 3 +-- > >>> 1 file changed, 1 insertion(+), 2 deletions(-) > >>> > >>> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c > >>> index a48e3f90..5c73e1d 100644 > >>> --- a/drivers/usb/typec/tcpm/tcpm.c > >>> +++ b/drivers/usb/typec/tcpm/tcpm.c > >>> @@ -2797,8 +2797,7 @@ 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; > >>> + port->hard_reset_count = 0; > >>> > >> > >> Doesn't that mean that the state machine will never enter > >> error recovery ? > >> > > I think it does't affect the error recovery. > > All error recovery seems to check pd_capable flag. > > > >>From my below case, it's A to C cable only. There is no USBPD contract > > will be estabilished. > > > > This case occurred following by the below test condition > > Cable -> A to C (default Rp bind to vbus) connected to PC. > > 1. first time plugged in the cable with PC > > It will make HARD_RESET_COUNT to be equal 2 > > 2. And then plug out. At that time HARD_RESET_COUNT is till 2. > > 3. next time plugged in again. > > Due to hard_reset_count is still 2 , after wait_cap_timeout, the state > > eventually changed to SNK_READY. > > But during the state transition, no hard_reset be sent. > > > > Defined in the USBPD policy engine, typec transition to USBPD, all > > variables must be reset included hard_reset_count. > > So it expected SNK must send hard_reset again. > > > > The original code defined hard_reset_count must be reset only when > > tcpm_port_is_disconnected. > > > > It doesn't make sense that it only occurred in some scenario. > > If tcpm_detach is called, hard_reset count must be reset also. > > > > If a hard reset fails, the state machine may cycle through states > HARD_RESET_SEND, HARD_RESET_START, SRC_HARD_RESET_VBUS_OFF, > SRC_HARD_RESET_VBUS_ON back to SRC_UNATTACHED. In this state, > tcpm_src_detach() and with it tcpm_detach() is called. The hard > reset counter is incremented in HARD_RESET_SEND. If tcpm_detach() > resets the counter, the state machine will keep cycling through hard > resets without ever entering the error recovery state. I am not > entirely sure where the counter should be reset, but tcpm_detach() > seems to be the wrong place. This case you specified means locally error occurred. It intended to re-run the state machine from typec to USBPD. >From my understanding, hard_reset_count to be reset is reasonable. The normal stare from the state transition you specified is HARD_RESET_SEND, HARD_RESET_START -> SRC_HARD_RESET_VBUS_OFF, SRC_HARD_RESET_VBUS_ON -> received VBUS_EVENT then go to SRC_STARTUP. > > Guenter > > >> Guenter > >> > >>> tcpm_reset_port(port); > >>> } > >>> -- > >>> 2.7.4 > >>> >
