Hi Gabor,
While HI-Zing CC pins disrupts power for batteryless devices, not Hi-Zing CC pins would prevent clean error recovery for self powered devices. Hi-Zing CC pins would make the port partner recognize it as disconnect and will result in bringup the connection back cleanly.
How about leveraging "self-powered" device tree property and Hi-Zing CC pins only when using "self-powered" ?
Regards, Badhri
On Wed, Jan 17, 2024 at 8:07 AM Gábor Stefanik netrolller.3d@gmail.com wrote:
This will break operation of batteryless devices relying on a USB Type-C port for their power needs, as the port reset upon controller initialization will cause power to be cut to the device, resulting in a boot loop. Devices using the FUSB302C port controller are especially severely affected, as upon losing power, this controller can retain CC states for a very long time (potentially forever if some parasitic source of power is present), requiring a full mechanical disconnect-reconnect cycle before the device receives power again.
While the USB Type C specification does require this behavior, I would consider this an oversight in the standard (perhaps left over from when USB Power Delivery was still going to be USB Battery Charging 2.0).
Badhri Jagan Sridharan badhri@google.com ezt írta (időpont: 2024. jan. 17., Sze, 12:38):
This reverts commit 1e35f074399dece73d5df11847d4a0d7a6f49434.
Given that ERROR_RECOVERY calls into PORT_RESET for Hi-Zing the CC pins, setting CC pins to default state during PORT_RESET breaks error recovery.
4.5.2.2.2.1 ErrorRecovery State Requirements The port shall not drive VBUS or VCONN, and shall present a high-impedance to ground (above zOPEN) on its CC1 and CC2 pins.
Hi-Zing the CC pins is the inteded behavior for PORT_RESET. CC pins are set to default state after tErrorRecovery in PORT_RESET_WAIT_OFF.
4.5.2.2.2.2 Exiting From ErrorRecovery State A Sink shall transition to Unattached.SNK after tErrorRecovery. A Source shall transition to Unattached.SRC after tErrorRecovery.
Cc: stable@kernel.org Fixes: 1e35f074399d ("usb: typec: tcpm: fix cc role at port reset") Signed-off-by: Badhri Jagan Sridharan badhri@google.com
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 5945e3a2b0f7..9d410718eaf4 100644 --- a/drivers/usb/typec/tcpm/tcpm.c +++ b/drivers/usb/typec/tcpm/tcpm.c @@ -4876,8 +4876,7 @@ static void run_state_machine(struct tcpm_port *port) break; case PORT_RESET: tcpm_reset_port(port);
tcpm_set_cc(port, tcpm_default_state(port) == SNK_UNATTACHED ?TYPEC_CC_RD : tcpm_rp_cc(port));
tcpm_set_cc(port, TYPEC_CC_OPEN); tcpm_set_state(port, PORT_RESET_WAIT_OFF, PD_T_ERROR_RECOVERY); break;base-commit: 933bb7b878ddd0f8c094db45551a7daddf806e00
2.43.0.429.g432eaa2c6b-goog