From 73134a1b817d66b9ded9c84776a1b81f672bab9d Mon Sep 17 00:00:00 2001
From: Chad Condon <chad@condon.tech>
Date: Wed, 5 Mar 2025 22:01:00 -0800
Subject: [PATCH] Retry I2C harder

---
 src/klipper_sgp40/__init__.py | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/src/klipper_sgp40/__init__.py b/src/klipper_sgp40/__init__.py
index 5c5b6f7..2b72fb9 100644
--- a/src/klipper_sgp40/__init__.py
+++ b/src/klipper_sgp40/__init__.py
@@ -11,7 +11,8 @@
 from logging import ERROR, WARNING
 from struct import unpack_from
 
-from .. import bus  # type:ignore
+from ...serialhdl import error  # type: ignore
+from .. import bus  # type: ignore
 from .gia import GasIndexAlgorithm
 
 SGP40_CHIP_ADDR = 0x59
@@ -22,6 +23,27 @@
 MEASURE_RAW_CMD_PREFIX = [0x26, 0x0F]
 
 
+# Hack i2c to attempt more retries.
+def _get_response(self, cmds, cmd_queue, minclock=0, reqclock=0):
+    retries = 15
+    retry_delay = 0.010
+    while 1:
+        for cmd in cmds[:-1]:
+            self.serial.raw_send(cmd, minclock, reqclock, cmd_queue)
+        self.serial.raw_send_wait_ack(cmds[-1], minclock, reqclock, cmd_queue)
+        params = self.last_params
+        if params is not None:
+            self.serial.register_response(None, self.name, self.oid)
+            return params
+        if retries <= 0:
+            self.serial.register_response(None, self.name, self.oid)
+            raise error("Unable to obtain '%s' response" % (self.name,))
+        reactor = self.serial.reactor
+        reactor.pause(reactor.monotonic() + retry_delay)
+        retries -= 1
+        retry_delay *= 2.0
+
+
 def _generate_crc(data):
     # From SGP40 data sheet
     crc = 0xFF
@@ -184,6 +206,8 @@ def _handle_connect(self):
 
         self._init_sgp40()
 
+        self.i2c.i2c_read_cmd._xmit_helper.get_response = _get_response
+
         self.reactor.update_timer(self.step_timer, self.reactor.NOW)
 
     def _handle_ready(self):