On 10/2/20 6:31 AM, Greg KH wrote: > On Tue, Sep 15, 2020 at 11:07:18AM +0800, ChiYuan Huang wrote: >> Hi, Guenter: >> >> ChiYuan Huang <u0084500@xxxxxxxxx> 於 2020年9月6日 週日 下午11:22寫道： >>> >>> Guenter Roeck <linux@xxxxxxxxxxxx> 於 2020年9月5日 週六 下午11:51寫道： >>>> >>>> On 9/4/20 6:24 PM, ChiYuan Huang wrote: >>>>> 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 could be a local error (with the local hardware), or with the >>>> remote partner not accepting the reset. We only know that an 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. >>>>> >>>> The operational word is "normal". Error recovery is expected to handle >>>> situations which are not normal. >>> >>> Following by the USBPD 3.0 revision 1.2, section 8.3.3.24.1 >>> The ErrorRecovery state is used to electronically disconnect Port >>> Partner using the USB Type-C connector. >>> And there's one sentence to be said "The ErrorRecovery staste shall >>> map to USB Type-C Error Recovery state operations". >>> I also read ErrorRecovery state in USB TYPE-C 1.3 spec. >>> Section 4.5.2.2.2.1 ErrorRecovery state requirement listed the below text. >>> The port shall not drive VBUS or VCONN, and shall present a >>> high-impedance to ground (above >>> zOPEN) on its CC1 and CC2 pins. >>> Section 4.5.2.2.2.2 Exiting from the error recovery state >>> I read the description. The roughly meaning is to change the state to >>> Unattached(Src or Snk) after tErrorRecovery. >>> >>> Summary the above text. >>> Reset HardResetCounter is ok in tcpm_detach. >>> My patch is just to relax the counter reset conditions during tcpm_detach(). >>> If not, it will check tcpm_port_is_disconnected(). >>> And only two scenario, the hard reset count will be cleared to 0 at this case. >>> 1) port not attached and cc1=open and cc2=open >>> 2) port attached and either (polarity=cc1, cc1=open) or (polarity=cc2, cc2=open) >>> >>> I think this judgement is narrow in tcpm_detach case. >>> >>>> >>>> I don't question the need to reset the counter. The only question >>>> is where and when to reset it. >>>> >>> I re-check all tcpm code for hard reset counter about the increment and reset. >>> They all meets USBPD spec. Only the detach case, I'm wondering why it >>> need to add the check for tcpm_port_is_disconnected(). >>> >> Below's the real case log. >> [ 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 [delayed 20 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 [delayed 200 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 [delayed 240 ms] >> >> You can see the next type c attach log. >> It directly change state from SNK_WAIT_CAPABILITIES to SNK_READY due >> to not reset hard_reset_count. >> >> It's easy to reproduce if you plugout USB Adapater w/i AtoC cable connected. > > What ever happened with this patch, is there still disagreement? > Yes, there is. I wouldn't have added the conditional without reason, and I am concerned that removing it entirely will open another problem. Feel free to apply, though - I can't prove that my concern is valid, and after all we'll get reports from the field later if it is. Guenter
