stepcompress: Using normal message priority system during homing

The endstop homing system requires all queue_step commands be in the
MCU's 'move queue' before endstop checking starts.  Use the normal
message priority system to request that stepper queue_step commands
are received prior to the start of the end_stop_home command.  This
simplifies the code and removes the need for special serial queue
flushing.

This also fixes a bug in homing operations that take longer than 2^31
clock ticks.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

3 files changed, 21 insertions, 8 deletions

diff --git a/klippy/chelper.py b/klippy/chelper.py
index 4384fe28..3603d839 100644
--- a/klippy/chelper.py
+++ b/klippy/chelper.py
@@ -33,6 +33,7 @@ defs_stepcompress = """
         , double accel_multiplier, double step_dist, double height
         , double closestxy_d, double closest_height2, double movez_r);
     void stepcompress_reset(struct stepcompress *sc, uint64_t last_step_clock);
+    void stepcompress_set_homing(struct stepcompress *sc, uint64_t homing_clock);
     void stepcompress_queue_msg(struct stepcompress *sc
         , uint32_t *data, int len);
     uint32_t stepcompress_get_errors(struct stepcompress *sc);
diff --git a/klippy/mcu.py b/klippy/mcu.py
index c9927841..6fc2db0d 100644
--- a/klippy/mcu.py
+++ b/klippy/mcu.py
@@ -58,7 +58,10 @@ class MCU_stepper:
         self._mcu_position_offset = pos - self.commanded_position
     def get_mcu_position(self):
         return self.commanded_position + self._mcu_position_offset
-    def note_stepper_stop(self):
+    def note_homing_start(self, homing_clock):
+        self.ffi_lib.stepcompress_set_homing(self._stepqueue, homing_clock)
+    def note_homing_finalized(self):
+        self.ffi_lib.stepcompress_set_homing(self._stepqueue, 0)
         self.ffi_lib.stepcompress_reset(self._stepqueue, 0)
     def reset_step_clock(self, mcu_time):
         clock = int(mcu_time * self._mcu_freq)
@@ -144,11 +147,9 @@ class MCU_endstop:
         msg = self._home_cmd.encode(
             self._oid, clock, rest_ticks, 1 ^ self._invert)
         self._mcu.send(msg, reqclock=clock, cq=self._cmd_queue)
+        self._stepper.note_homing_start(clock)
     def home_finalize(self, mcu_time):
-        # XXX - this flushes the serial port of messages ready to be
-        # sent, but doesn't flush messages if they had an unmet minclock
-        self._mcu.serial.send_flush()
-        self._stepper.note_stepper_stop()
+        self._stepper.note_homing_finalized()
         self._home_timeout_clock = int(mcu_time * self._mcu_freq)
     def home_wait(self):
         eventtime = time.time()
diff --git a/klippy/stepcompress.c b/klippy/stepcompress.c
index 6bcdb284..2100aa3e 100644
--- a/klippy/stepcompress.c
+++ b/klippy/stepcompress.c
@@ -34,7 +34,7 @@ struct stepcompress {
     // Error checking
     uint32_t errors;
     // Message generation
-    uint64_t last_step_clock;
+    uint64_t last_step_clock, homing_clock;
     struct list_head msg_queue;
     uint32_t queue_step_msgid, set_next_step_dir_msgid, oid;
     int sdir, invert_sdir;
@@ -339,6 +339,9 @@ stepcompress_flush(struct stepcompress *sc, uint64_t move_clock)
             uint32_t ticks = move.add*addfactor + move.interval*move.count;
             sc->last_step_clock += ticks;
         }
+        if (sc->homing_clock)
+            // When homing, all steps should be sent prior to homing_clock
+            qm->min_clock = qm->req_clock = sc->homing_clock;
         list_add_tail(&qm->node, &sc->msg_queue);
 
         if (sc->queue_pos + move.count >= sc->queue_next) {
@@ -359,7 +362,7 @@ set_next_step_dir(struct stepcompress *sc, int sdir)
         sc->set_next_step_dir_msgid, sc->oid, sdir ^ sc->invert_sdir
     };
     struct queue_message *qm = message_alloc_and_encode(msg, 3);
-    qm->req_clock = sc->last_step_clock;
+    qm->req_clock = sc->homing_clock ?: sc->last_step_clock;
     list_add_tail(&qm->node, &sc->msg_queue);
 }
 
@@ -557,6 +560,14 @@ stepcompress_reset(struct stepcompress *sc, uint64_t last_step_clock)
     sc->sdir = -1;
 }
 
+// Indicate the stepper is in homing mode (or done homing if zero)
+void
+stepcompress_set_homing(struct stepcompress *sc, uint64_t homing_clock)
+{
+    stepcompress_flush(sc, UINT64_MAX);
+    sc->homing_clock = homing_clock;
+}
+
 // Queue an mcu command to go out in order with stepper commands
 void
 stepcompress_queue_msg(struct stepcompress *sc, uint32_t *data, int len)
@@ -564,7 +575,7 @@ stepcompress_queue_msg(struct stepcompress *sc, uint32_t *data, int len)
     stepcompress_flush(sc, UINT64_MAX);
 
     struct queue_message *qm = message_alloc_and_encode(data, len);
-    qm->req_clock = sc->last_step_clock;
+    qm->req_clock = sc->homing_clock ?: sc->last_step_clock;
     list_add_tail(&qm->node, &sc->msg_queue);
 }