diff options
Diffstat (limited to 'common/usb_pd_protocol.c')
| -rw-r--r-- | common/usb_pd_protocol.c | 61 |
1 files changed, 44 insertions, 17 deletions
diff --git a/common/usb_pd_protocol.c b/common/usb_pd_protocol.c index 7d9ade5e2c..8ca0bbb6fc 100644 --- a/common/usb_pd_protocol.c +++ b/common/usb_pd_protocol.c @@ -94,13 +94,13 @@ static const int debug_level; #define PD_SNK_CAP_RETRIES 3 /* - * The time that we allow the source to send any messages after an explicit - * contract is established. 200ms was chosen somewhat arbitrarily as it should - * be long enough for sources to decide to send a message if they were going to, - * but not so long that a "low power charger connected" notification would be - * shown in the chrome OS UI. + * The time that we allow the port partner to send any messages after an + * explicit contract is established. 200ms was chosen somewhat arbitrarily as + * it should be long enough for sources to decide to send a message if they were + * going to, but not so long that a "low power charger connected" notification + * would be shown in the chrome OS UI. */ -#define SNK_READY_HOLD_OFF_US (200 * MSEC) +#define READY_HOLD_OFF_US (200 * MSEC) enum vdm_states { VDM_STATE_ERR_BUSY = -3, @@ -243,12 +243,12 @@ static struct pd_protocol { uint8_t rev; #endif /* - * Time at which the port acting as a sink can start to request for - * higher power and interrogate the port partner. Some port partners - * are really chatty after the initial request so we allow this time for - * the port partner to send any messages in order to avoid a collision. + * Some port partners are really chatty after an explicit contract is + * established. Therefore, we allow this time for the port partner to + * send any messages in order to avoid a collision of sending messages + * of our own. */ - uint64_t snk_ready_holdoff_timer; + uint64_t ready_state_holdoff_timer; } pd[CONFIG_USB_PD_PORT_COUNT]; #ifdef CONFIG_COMMON_RUNTIME @@ -692,8 +692,8 @@ static inline void set_state(int port, enum pd_states next_state) ppc_clear_oc_event_counter(port); } #endif /* CONFIG_USBC_PPC */ - /* Clear the SNK_READY holdoff timer. */ - pd[port].snk_ready_holdoff_timer = 0; + /* Clear the holdoff timer since the port is disconnected. */ + pd[port].ready_state_holdoff_timer = 0; /* * We should not clear any flags when transitioning back to the @@ -1717,11 +1717,14 @@ static void handle_ctrl_request(int port, uint16_t head, } else if (pd[port].power_role == PD_ROLE_SINK) { /* * Give the source some time to send any messages before - * we start our interrogation. + * we start our interrogation. Add some jitter of up to + * 100ms, taken from the current system time, to prevent + * multiple collisions. */ if (pd[port].task_state == PD_STATE_SNK_TRANSITION) - pd[port].snk_ready_holdoff_timer = - get_time().val + SNK_READY_HOLD_OFF_US; + pd[port].ready_state_holdoff_timer = + get_time().val + READY_HOLD_OFF_US + + (get_time().le.lo % (100 * MSEC)); set_state(port, PD_STATE_SNK_READY); pd_set_input_current_limit(port, pd[port].curr_limit, @@ -3281,6 +3284,18 @@ void pd_task(void *u) res = send_control(port, PD_CTRL_PS_RDY); if (res >= 0) { timeout = 10*MSEC; + + /* + * Give the sink some time to send any messages + * before we may send messages of our own. Add + * some jitter of up to 100ms, taken from the + * current system time, to prevent multiple + * collisions. + */ + pd[port].ready_state_holdoff_timer = + get_time().val + READY_HOLD_OFF_US + + (get_time().le.lo % (100 * MSEC)); + /* it'a time to ping regularly the sink */ set_state(port, PD_STATE_SRC_READY); } else { @@ -3292,6 +3307,17 @@ void pd_task(void *u) timeout = PD_T_SOURCE_ACTIVITY; /* + * Don't send any traffic yet until our holdoff timer + * has expired. Some devices are chatty once we reach + * the SRC_READY state and we may end up in a collision + * of messages if we try to immediately send our + * interrogations. + */ + if (get_time().val <= + pd[port].ready_state_holdoff_timer) + break; + + /* * Don't send any PD traffic if we woke up due to * incoming packet or if VDO response pending to avoid * collisions. @@ -3791,7 +3817,8 @@ void pd_task(void *u) * of messages if we try to immediately send our * interrogations. */ - if (get_time().val <= pd[port].snk_ready_holdoff_timer) + if (get_time().val <= + pd[port].ready_state_holdoff_timer) break; /* |