From 9a4618b05b9f1093908c2153c719c5eb5d4a79ee Mon Sep 17 00:00:00 2001
From: Joshua Diamond <josh@windowoffire.com>
Date: Mon, 1 Feb 2021 19:12:41 -0500
Subject: Address wake from sleep instability (#11450)

* resolve race condition between suspend and wake in LUFA

* avoid multiple calls to suspend_power_down() / suspend_wakeup_init()

* Remove duplicate suspend_power_down_kb() call

* pause on wakeup to wait for USB state to settle

* need the repeated suspend_power_down() (that's where the sleep is)

* more efficient implementation

* fine tune the pause after sending wakeup

* speculative chibios version of pause-after-wake

* make wakeup delay configurable, and adjust value

* better location for wakeup delay
---
 tmk_core/common/avr/suspend.c        |  1 -
 tmk_core/common/suspend.h            |  4 ++++
 tmk_core/protocol/chibios/usb_main.c | 11 +++++++++++
 tmk_core/protocol/lufa/lufa.c        | 24 ++++++++++++++++++++----
 4 files changed, 35 insertions(+), 5 deletions(-)

(limited to 'tmk_core')

diff --git a/tmk_core/common/avr/suspend.c b/tmk_core/common/avr/suspend.c
index 9db0e0064a..b784a0835d 100644
--- a/tmk_core/common/avr/suspend.c
+++ b/tmk_core/common/avr/suspend.c
@@ -102,7 +102,6 @@ static void power_down(uint8_t wdto) {
 #    if defined(RGBLIGHT_SLEEP) && defined(RGBLIGHT_ENABLE)
     rgblight_suspend();
 #    endif
-    suspend_power_down_kb();
 
     // TODO: more power saving
     // See PicoPower application note
diff --git a/tmk_core/common/suspend.h b/tmk_core/common/suspend.h
index 766df95aa1..9d17d984ed 100644
--- a/tmk_core/common/suspend.h
+++ b/tmk_core/common/suspend.h
@@ -12,3 +12,7 @@ void suspend_wakeup_init_user(void);
 void suspend_wakeup_init_kb(void);
 void suspend_power_down_user(void);
 void suspend_power_down_kb(void);
+
+#ifndef USB_SUSPEND_WAKEUP_DELAY
+#    define USB_SUSPEND_WAKEUP_DELAY 200
+#endif
diff --git a/tmk_core/protocol/chibios/usb_main.c b/tmk_core/protocol/chibios/usb_main.c
index cb7aeb23b2..13b1e34d28 100644
--- a/tmk_core/protocol/chibios/usb_main.c
+++ b/tmk_core/protocol/chibios/usb_main.c
@@ -708,6 +708,17 @@ void init_usb_driver(USBDriver *usbp) {
 void restart_usb_driver(USBDriver *usbp) {
     usbStop(usbp);
     usbDisconnectBus(usbp);
+
+#if USB_SUSPEND_WAKEUP_DELAY > 0
+    // Some hubs, kvm switches, and monitors do
+    // weird things, with USB device state bouncing
+    // around wildly on wakeup, yielding race
+    // conditions that can corrupt the keyboard state.
+    //
+    // Pause for a while to let things settle...
+    wait_ms(USB_SUSPEND_WAKEUP_DELAY);
+#endif
+
     usbStart(usbp, &usbcfg);
     usbConnectBus(usbp);
 }
diff --git a/tmk_core/protocol/lufa/lufa.c b/tmk_core/protocol/lufa/lufa.c
index 623aa33ff5..74e48222d0 100644
--- a/tmk_core/protocol/lufa/lufa.c
+++ b/tmk_core/protocol/lufa/lufa.c
@@ -435,7 +435,9 @@ void EVENT_USB_Device_Suspend() {
  */
 void EVENT_USB_Device_WakeUp() {
     print("[W]");
+#if defined(NO_USB_STARTUP_CHECK)
     suspend_wakeup_init();
+#endif
 
 #ifdef SLEEP_LED_ENABLE
     sleep_led_disable();
@@ -1073,12 +1075,26 @@ int main(void) {
     print("Keyboard start.\n");
     while (1) {
 #if !defined(NO_USB_STARTUP_CHECK)
-        while (USB_DeviceState == DEVICE_STATE_Suspended) {
+        if (USB_DeviceState == DEVICE_STATE_Suspended) {
             print("[s]");
-            suspend_power_down();
-            if (USB_Device_RemoteWakeupEnabled && suspend_wakeup_condition()) {
-                USB_Device_SendRemoteWakeup();
+            while (USB_DeviceState == DEVICE_STATE_Suspended) {
+                suspend_power_down();
+                if (USB_Device_RemoteWakeupEnabled && suspend_wakeup_condition()) {
+                    USB_Device_SendRemoteWakeup();
+                    clear_keyboard();
+
+#    if USB_SUSPEND_WAKEUP_DELAY > 0
+                    // Some hubs, kvm switches, and monitors do
+                    // weird things, with USB device state bouncing
+                    // around wildly on wakeup, yielding race
+                    // conditions that can corrupt the keyboard state.
+                    //
+                    // Pause for a while to let things settle...
+                    wait_ms(USB_SUSPEND_WAKEUP_DELAY);
+#    endif
+                }
             }
+            suspend_wakeup_init();
         }
 #endif
 
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