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usb: typec: tcpm: Try PD-2.0 if sink does not respond to 3.0 source-caps 

PD 2.0 sinks are supposed to accept src-capabilities with a 3.0 header and
simply ignore any src PDOs which the sink does not understand such as PPS
but some 2.0 sinks instead ignore the entire PD_DATA_SOURCE_CAP message,
causing contract negotiation to fail.

This commit fixes such sinks not working by re-trying the contract
negotiation with PD-2.0 source-caps messages if we don't have a contract
after PD_N_HARD_RESET_COUNT hard-reset attempts.

The problem fixed by this commit was noticed with a Type-C to VGA dongle.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
hifive-unleashed-5.1
Hans de Goede 2019-03-16 16:57:12 +01:00 committed by Greg Kroah-Hartman
parent 40fc165304
commit 976daf9d11
1 changed files with 26 additions and 1 deletions
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27
drivers/usb/typec/tcpm/tcpm.c
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@ -37,6 +37,7 @@
S(SRC_ATTACHED), \
S(SRC_STARTUP), \
S(SRC_SEND_CAPABILITIES), \
S(SRC_SEND_CAPABILITIES_TIMEOUT), \
S(SRC_NEGOTIATE_CAPABILITIES), \
S(SRC_TRANSITION_SUPPLY), \
S(SRC_READY), \
@ -2966,10 +2967,34 @@ static void run_state_machine(struct tcpm_port *port)
/* port->hard_reset_count = 0; */
port->caps_count = 0;
port->pd_capable = true;
tcpm_set_state_cond(port, hard_reset_state(port),
tcpm_set_state_cond(port, SRC_SEND_CAPABILITIES_TIMEOUT,
PD_T_SEND_SOURCE_CAP);
}
break;
case SRC_SEND_CAPABILITIES_TIMEOUT:
/*
* Error recovery for a PD_DATA_SOURCE_CAP reply timeout.
*
* PD 2.0 sinks are supposed to accept src-capabilities with a
* 3.0 header and simply ignore any src PDOs which the sink does
* not understand such as PPS but some 2.0 sinks instead ignore
* the entire PD_DATA_SOURCE_CAP message, causing contract
* negotiation to fail.
*
* After PD_N_HARD_RESET_COUNT hard-reset attempts, we try
* sending src-capabilities with a lower PD revision to
* make these broken sinks work.
*/
if (port->hard_reset_count < PD_N_HARD_RESET_COUNT) {
tcpm_set_state(port, HARD_RESET_SEND, 0);
} else if (port->negotiated_rev > PD_REV20) {
port->negotiated_rev--;
port->hard_reset_count = 0;
tcpm_set_state(port, SRC_SEND_CAPABILITIES, 0);
} else {
tcpm_set_state(port, hard_reset_state(port), 0);
}
break;
case SRC_NEGOTIATE_CAPABILITIES:
ret = tcpm_pd_check_request(port);
if (ret < 0) {