Suppress transient I2C failure messages

2 files changed, 13 insertions, 12 deletions

diff --git a/woferclock/README b/woferclock/README
index 910ca47..be4bb6b 100644
--- a/woferclock/README
+++ b/woferclock/README
@@ -10,6 +10,3 @@ python
 
 To overclock:
 ./woferclock_cpu
-
-Known issues:
-Depending on system version and/or kernel version, the VPD write step may spew write errors.  This is normal, and the VPD is successfully updated if no VPD mismatch error is printed at the end of the update process.
diff --git a/woferclock/write_vpd b/woferclock/write_vpd
index 0105d83..225d32a 100755
--- a/woferclock/write_vpd
+++ b/woferclock/write_vpd
@@ -5,7 +5,9 @@
 
 import sys
 import os
+import time
 import binascii
+import subprocess
 
 eeprom_bus = int(sys.argv[1])
 if sys.argv[2].startswith("0x") or sys.argv[2].startswith("0X"):
@@ -48,15 +50,17 @@ for i in range(0, vpd_length, 2):
         address_low = hex(address & 255)
         command = "i2cset -y " + str(eeprom_bus) + " 0x" + format(eeprom_address, '02x') + " " +  address_high + " " + address_low + " 0x" + raw_data[i:(i+2)] + " i"
         i2c_ret = os.system(command)
-        exit_code = os.WEXITSTATUS(i2c_ret)
-        if exit_code != 0:
-            # Retry
-            i2c_ret = os.system(command)
-            exit_code = os.WEXITSTATUS(i2c_ret)
-        if exit_code != 0:
-            print "[ERROR] Write failed!"
-            print "\tCommand was: " + command
-            sys.exit(1)
+        try:
+            subprocess.check_call(command, stderr=subprocess.STDOUT, shell=True)
+        except:
+            # Retry, giving the SEEPROM some time to recover
+            time.sleep(0.1)
+            try:
+                subprocess.check_call(command, shell=True)
+            except:
+                print "[ERROR] Write failed!"
+                print "\tCommand was: " + command
+                sys.exit(1)
     address = address + 1
     sys.stdout.write(format(address, '05d') + " / " + format((vpd_length / 2), '05d') + "\r")
     sys.stdout.flush()