This is a note to let you know that I've just added the patch titled

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

to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 976daf9d1199932df80e7b04546d1a1bd4ed5ece Mon Sep 17 00:00:00 2001

From: Hans de Goede hdegoede@redhat.com Date: Sat, 16 Mar 2019 16:57:12 +0100 Subject: 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 --- drivers/usb/typec/tcpm/tcpm.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c index 0f62db091d8d..a2233d72ae7c 100644 --- a/drivers/usb/typec/tcpm/tcpm.c +++ b/drivers/usb/typec/tcpm/tcpm.c @@ -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) {