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authorDiana Z <dzigterman@chromium.org>2021-02-24 17:02:52 -0700
committerCommit Bot <commit-bot@chromium.org>2021-03-16 21:36:15 +0000
commit91ad865eaf32295240b62b5fbbd402c2023c187c (patch)
tree8356a43777aa5384ff60e9e894206e17c041b6be
parent657c9f952da217d18e55fb139e5e59f3cd58c670 (diff)
downloadchrome-ec-91ad865eaf32295240b62b5fbbd402c2023c187c.tar.gz
TCPMv2: Debounce Vbus loss when FRS is enabled
A hub may send a Fast Role Swap signal when Vbus is less than vSafe5V, so allow a 5ms debounce after Vbus loss for the signal to come in before we declare the connection detached. BRANCH=None BUG=b:180453483 TEST=on voxel, confirm FRS behaves normally Signed-off-by: Diana Z <dzigterman@chromium.org> Change-Id: If56106660c0a2bf82e28b91129bc9dd367ebc8fe Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2718838 Tested-by: Eric Herrmann <eherrmann@chromium.org> Reviewed-by: Eric Herrmann <eherrmann@chromium.org> Reviewed-by: Denis Brockus <dbrockus@chromium.org>
-rw-r--r--common/usbc/usb_tc_drp_acc_trysrc_sm.c49
-rw-r--r--include/usb_pd.h7
2 files changed, 50 insertions, 6 deletions
diff --git a/common/usbc/usb_tc_drp_acc_trysrc_sm.c b/common/usbc/usb_tc_drp_acc_trysrc_sm.c
index 58fc085a61..50211feacf 100644
--- a/common/usbc/usb_tc_drp_acc_trysrc_sm.c
+++ b/common/usbc/usb_tc_drp_acc_trysrc_sm.c
@@ -2427,6 +2427,46 @@ static void tc_attached_snk_entry(const int port)
tcpm_debug_accessory(port, 1);
}
+/*
+ * Check whether Vbus has been removed on this port, accounting for some Vbus
+ * debounce if FRS is enabled.
+ *
+ * Returns true if a new state was set and the calling run should exit.
+ */
+static bool tc_snk_check_vbus_removed(const int port)
+{
+ if (IS_ENABLED(CONFIG_USB_PD_FRS)) {
+ /*
+ * Debounce Vbus presence when FRS is enabled. Note that we may
+ * lose Vbus before the FRS signal comes in to let us know
+ * we're PR swapping, but we must still transition to unattached
+ * within tSinkDisconnect.
+ *
+ * We may safely re-use the Vbus debounce timer here
+ * since a PR swap would no longer be in progress when Vbus
+ * removal is checked.
+ */
+ if (pd_check_vbus_level(port, VBUS_REMOVED)) {
+ if (pd_timer_is_disabled(port,
+ TC_TIMER_VBUS_DEBOUNCE)) {
+ pd_timer_enable(port, TC_TIMER_VBUS_DEBOUNCE,
+ PD_T_FRS_VBUS_DEBOUNCE);
+ } else if (pd_timer_is_expired(port,
+ TC_TIMER_VBUS_DEBOUNCE)) {
+ set_state_tc(port, TC_UNATTACHED_SNK);
+ return true;
+ }
+ } else {
+ pd_timer_disable(port, TC_TIMER_VBUS_DEBOUNCE);
+ }
+ } else if (pd_check_vbus_level(port, VBUS_REMOVED)) {
+ set_state_tc(port, TC_UNATTACHED_SNK);
+ return true;
+ }
+
+ return false;
+}
+
static void tc_attached_snk_run(const int port)
{
#ifdef CONFIG_USB_PE_SM
@@ -2465,6 +2505,7 @@ static void tc_attached_snk_run(const int port)
pd_timer_is_expired(port, TC_TIMER_VBUS_DEBOUNCE)) {
/* PR Swap is no longer in progress */
TC_CLR_FLAG(port, TC_FLAGS_PR_SWAP_IN_PROGRESS);
+ pd_timer_disable(port, TC_TIMER_VBUS_DEBOUNCE);
/*
* AutoDischargeDisconnect was turned off when we
@@ -2485,10 +2526,8 @@ static void tc_attached_snk_run(const int port)
/*
* Detach detection
*/
- if (pd_check_vbus_level(port, VBUS_REMOVED)) {
- set_state_tc(port, TC_UNATTACHED_SNK);
+ if (tc_snk_check_vbus_removed(port))
return;
- }
if (!pe_is_explicit_contract(port))
sink_power_sub_states(port);
@@ -2577,10 +2616,8 @@ static void tc_attached_snk_run(const int port)
#else /* CONFIG_USB_PE_SM */
/* Detach detection */
- if (pd_check_vbus_level(port, VBUS_REMOVED)) {
- set_state_tc(port, TC_UNATTACHED_SNK);
+ if (tc_snk_check_vbus_removed(port))
return;
- }
/* Run Sink Power Sub-State */
sink_power_sub_states(port);
diff --git a/include/usb_pd.h b/include/usb_pd.h
index 81dbc3220a..ed15149441 100644
--- a/include/usb_pd.h
+++ b/include/usb_pd.h
@@ -246,6 +246,13 @@ enum pd_rx_errors {
#define PD_T_SYSJUMP (1000*MSEC) /* 1s */
#define PD_T_PR_SWAP_WAIT (100*MSEC) /* tPRSwapWait 100ms */
+/*
+ * Non-spec timer to prevent going Unattached if Vbus drops before a partner FRS
+ * signal comes through. This timer should be shorter than tSinkDisconnect
+ * (40ms) to ensure we still transition out of Attached.SNK in time.
+ */
+#define PD_T_FRS_VBUS_DEBOUNCE (5*MSEC)
+
/* number of edges and time window to detect CC line is not idle */
#define PD_RX_TRANSITION_COUNT 3
#define PD_RX_TRANSITION_WINDOW 20 /* between 12us and 20us */