usb: typec: tcpm: Prevent TCPM from looping in SRC_TRYWAIT
According to the spec the following is the condition
for exiting TryWait.SRC:
"The port shall transition to Attached.SRC when V BUS is at vSafe0V
and the SRC.Rd state is detected on exactly one of the CC pins for at
least tCCDebounce. The port shall transition to Unattached.SNK after
tDRPTry if neither of the CC1 or CC2 pins are in the SRC.Rd state"
TCPM at present keeps re-entering the SRC_TRYWAIT and keeps restarting
tDRPTry if the CC presents Rp and disconnects within tCCDebounce.
For example:
[ 447.164308] pending state change SRC_TRYWAIT -> SRC_ATTACHED @ 200 ms
[ 447.164386] CC1: 2 -> 0, CC2: 0 -> 0 [state SRC_TRYWAIT, polarity 0, disconnected]
[ 447.164406] state change SRC_TRYWAIT -> SRC_TRYWAIT
[ 447.164573] cc:=3
[ 447.191408] pending state change SRC_TRYWAIT -> SRC_TRYWAIT_UNATTACHED @ 100 ms
[ 447.191478] CC1: 0 -> 0, CC2: 0 -> 0 [state SRC_TRYWAIT, polarity 0, disconnected]
[ 447.207261] CC1: 0 -> 2, CC2: 0 -> 0 [state SRC_TRYWAIT, polarity 0, connected]
[ 447.207306] state change SRC_TRYWAIT -> SRC_TRYWAIT
[ 447.207485] cc:=3
[ 447.237283] pending state change SRC_TRYWAIT -> SRC_ATTACHED @ 200 ms
[ 447.237357] CC1: 2 -> 0, CC2: 0 -> 0 [state SRC_TRYWAIT, polarity 0, disconnected]
[ 447.237379] state change SRC_TRYWAIT -> SRC_TRYWAIT
[ 447.237532] cc:=3
[ 447.263219] pending state change SRC_TRYWAIT -> SRC_TRYWAIT_UNATTACHED @ 100 ms
[ 447.263289] CC1: 0 -> 0, CC2: 0 -> 0 [state SRC_TRYWAIT, polarity 0, disconnected]
[ 447.280926] CC1: 0 -> 2, CC2: 0 -> 0 [state SRC_TRYWAIT, polarity 0, connected]
[ 447.280970] state change SRC_TRYWAIT -> SRC_TRYWAIT
[ 447.281158] cc:=3
[ 447.307767] pending state change SRC_TRYWAIT -> SRC_ATTACHED @ 200 ms
[ 447.307838] CC1: 2 -> 0, CC2: 0 -> 0 [state SRC_TRYWAIT, polarity 0, disconnected]
[ 447.307858] state change SRC_TRYWAIT -> SRC_TRYWAIT
In TCPM, tDRPTry is set tp 100ms (min 75ms and max 150ms)
and tCCdebounce is set to 200ms (min 100ms and max 200ms).
To overcome the issue, record the time at which the port
enters TryWait.SRC(SRC_TRYWAIT) and re-enter SRC_TRYWAIT only when CC keeps
debouncing within tDRPTry.
Bug: 64261058
Signed-off-by: Badhri Jagan Sridharan <Badhri@google.com>
Change-Id: Ia32fc34220f681a14250596704435e753ac5a624
1 file changed
