suspend: update wake up matrix after wake up delay

If USB_SUSPEND_WAKEUP_DELAY is set, the keyboard sleeps during wake up -
which can be up to multiple seconds. To handle key presses and releases
in that time frame we have to handle the following cases:

1. Key not pressed before suspend, and not pressed after wakeup → do
   nothing (normal case).
2. Key not pressed before suspend, but pressed after wakeup → set the
   wakeup_matrix bit to 1 (so that the press and release events would be
   suppressed).
3. Key pressed before suspend, but not pressed after wakeup → do nothing
   (the release event will be generated on the first matrix_task() call
   after the wakeup).
4. Key pressed before suspend, and still pressed after wakeup → do
   nothing (the release event will be generated some time later).

Signed-off-by: Stefan Kerkmann <karlk90@pm.me>
Co-authored-by: Sergey Vlasov <sigprof@gmail.com>

platforms/suspend.c

@@ -4,6 +4,7 @@
 #include "suspend.h"
 #include "matrix.h"
 
+extern matrix_row_t matrix_previous[MATRIX_ROWS];
 static matrix_row_t wakeup_matrix[MATRIX_ROWS];
 
 // TODO: Move to more correct location
@@ -48,14 +49,26 @@ bool suspend_wakeup_condition(void) {
     matrix_power_down();
 
     bool wakeup = false;
-    for (uint8_t r = 0; r < MATRIX_ROWS; r++) {
-        wakeup_matrix[r] = matrix_get_row(r);
-        wakeup |= wakeup_matrix[r] != 0;
+    for (uint8_t row = 0; row < MATRIX_ROWS; row++) {
+        wakeup_matrix[row] = matrix_get_row(row);
+        wakeup |= wakeup_matrix[row] != 0;
     }
 
     return wakeup;
 }
 
+void update_matrix_state_after_wakeup(void) {
+    matrix_power_up();
+    matrix_scan();
+    matrix_power_down();
+
+    for (uint8_t row = 0; row < MATRIX_ROWS; row++) {
+        const matrix_row_t current_row = matrix_get_row(row);
+        wakeup_matrix[row] |= current_row & ~matrix_previous[row];
+        matrix_previous[row] |= current_row;
+    }
+}
+
 bool keypress_is_wakeup_key(uint8_t row, uint8_t col) {
     return (wakeup_matrix[row] & ((matrix_row_t)1 << col));
 }

platforms/suspend.h

@@ -15,6 +15,7 @@ void suspend_power_down_kb(void);
 void suspend_power_down_quantum(void);
 
 bool keypress_is_wakeup_key(uint8_t row, uint8_t col);
+void update_matrix_state_after_wakeup(void);
 void wakeup_matrix_handle_key_event(uint8_t row, uint8_t col, bool pressed);
 
 #ifndef USB_SUSPEND_WAKEUP_DELAY

quantum/keyboard.c

@@ -571,6 +571,8 @@ static inline void generate_tick_event(void) {
     }
 }
 
+matrix_row_t matrix_previous[MATRIX_ROWS];
+
 /**
  * @brief This task scans the keyboards matrix and processes any key presses
  * that occur.
@@ -584,8 +586,6 @@ static bool matrix_task(void) {
         return false;
     }
 
-    static matrix_row_t matrix_previous[MATRIX_ROWS];
-
     matrix_scan();
     bool matrix_changed = false;
     for (uint8_t row = 0; row < MATRIX_ROWS && !matrix_changed; row++) {

tmk_core/protocol/chibios/chibios.c

@@ -193,6 +193,9 @@ void protocol_pre_task(void) {
                 //
                 // Pause for a while to let things settle...
                 wait_ms(USB_SUSPEND_WAKEUP_DELAY);
+                // ...and then update the wakeup matrix again as the waking key
+                // might have been released during the delay
+                update_matrix_state_after_wakeup();
 #    endif
             }
         }

tmk_core/protocol/lufa/lufa.c

@@ -836,6 +836,9 @@ void protocol_pre_task(void) {
                 //
                 // Pause for a while to let things settle...
                 wait_ms(USB_SUSPEND_WAKEUP_DELAY);
+                // ...and then update the wakeup matrix again as the waking key
+                // might have been released during the delay
+                update_matrix_state_after_wakeup();
 #    endif
             }
         }

tmk_core/protocol/vusb/protocol.c

@@ -145,6 +145,9 @@ void protocol_pre_task(void) {
                 //
                 // Pause for a while to let things settle...
                 wait_ms(USB_SUSPEND_WAKEUP_DELAY);
+                // ...and then update the wakeup matrix again as the waking key
+                // might have been released during the delay
+                update_matrix_state_after_wakeup();
 #    endif
             }
         }