From 06d91ddceeb94d26e00338236bb0d69ca0eef1fa Mon Sep 17 00:00:00 2001
From: Yuri D'Elia <wavexx@thregr.org>
Date: Thu, 17 Jun 2021 20:07:01 +0200
Subject: [PATCH 1/2] Handle Long-Press in the main loop

The longpress function is currently called within the temperature ISR,
which is bogus. Calling the longpress function at the wrong moment
can corrupt the menu buffers.

Move the call to the main loop by changing the logic slightly:

- still sample the lcd buttons inside the temperature ISR, which keeps
  scrollong/pressing responsive, but...
- set a flag to indicate that longpress has been triggered instead of
  calling the function directly
- call the function on the next manage_inactivity run

Combined with #3180 this removes _most_ unsafe operations out of the ISR
which can happen during a normal run (max/mintemp warnings are still an
exception).
---
 Firmware/Marlin_main.cpp | 11 +++++++++++
 Firmware/lcd.cpp         |  6 +++---
 Firmware/lcd.h           |  1 +
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/Firmware/Marlin_main.cpp b/Firmware/Marlin_main.cpp
index 92df0122d..1f7d46419 100755
--- a/Firmware/Marlin_main.cpp
+++ b/Firmware/Marlin_main.cpp
@@ -9901,6 +9901,17 @@ if(0)
   #endif
   check_axes_activity();
   mmu_loop();
+
+  // handle longpress
+  if(lcd_longpress_trigger)
+  {
+      // long press is not possible in modal mode, wait until ready
+      if (lcd_longpress_func && lcd_update_enabled)
+      {
+          lcd_longpress_func();
+          lcd_longpress_trigger = 0;
+      }
+  }
 }
 
 void kill(const char *full_screen_message, unsigned char id)
diff --git a/Firmware/lcd.cpp b/Firmware/lcd.cpp
index c3f2921d1..a52bdd3e8 100644
--- a/Firmware/lcd.cpp
+++ b/Firmware/lcd.cpp
@@ -728,6 +728,8 @@ void lcd_update_enable(uint8_t enabled)
 	}
 }
 
+bool lcd_longpress_trigger = 0;
+
 void lcd_buttons_update(void)
 {
     static uint8_t lcd_long_press_active = 0;
@@ -749,9 +751,7 @@ void lcd_buttons_update(void)
             else if (longPressTimer.expired(LONG_PRESS_TIME))
             {
                 lcd_long_press_active = 1;
-                //long press is not possible in modal mode
-                if (lcd_longpress_func && lcd_update_enabled)
-                    lcd_longpress_func();
+                lcd_longpress_trigger = 1;
             }
         }
     }
diff --git a/Firmware/lcd.h b/Firmware/lcd.h
index 12b162e75..65bb9dc92 100644
--- a/Firmware/lcd.h
+++ b/Firmware/lcd.h
@@ -110,6 +110,7 @@ extern uint32_t lcd_next_update_millis;
 extern uint8_t lcd_status_update_delay;
 
 extern lcd_longpress_func_t lcd_longpress_func;
+extern bool lcd_longpress_trigger;
 
 extern lcd_charsetup_func_t lcd_charsetup_func;
 

From 72b8f0d1e62e3cc4896c91d2b9140e280dc55134 Mon Sep 17 00:00:00 2001
From: Yuri D'Elia <wavexx@thregr.org>
Date: Sat, 19 Jun 2021 13:46:10 +0200
Subject: [PATCH 2/2] Add some warnings in lcd_buttons_update

---
 Firmware/lcd.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Firmware/lcd.cpp b/Firmware/lcd.cpp
index a52bdd3e8..37b70f1a1 100644
--- a/Firmware/lcd.cpp
+++ b/Firmware/lcd.cpp
@@ -730,6 +730,8 @@ void lcd_update_enable(uint8_t enabled)
 
 bool lcd_longpress_trigger = 0;
 
+// WARNING: this function is called from the temperature ISR.
+//          Only update flags, but do not perform any menu/lcd operation!
 void lcd_buttons_update(void)
 {
     static uint8_t lcd_long_press_active = 0;