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Commit 3cfce8b7 authored by Hans de Goede's avatar Hans de Goede Committed by Greg Kroah-Hartman
Browse files

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



[ Upstream commit 976daf9d1199932df80e7b04546d1a1bd4ed5ece ]

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: default avatarHans de Goede <hdegoede@redhat.com>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent fba4f7c1

drivers/usb/typec/tcpm.c

+26 −1
Original line number Diff line number Diff line
@@ -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),				\
@@ -2987,10 +2988,34 @@ 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) {