commit 01d69cfd2c959298656c20e9aee204859c92a53e
author Jian Ho <jianho@google.com> Thu Oct 20 17:36:00 2016 -0700
committer Jian Ho <jianho@google.com> Thu Oct 20 17:36:06 2016 -0700
tree 9afaca50118c50a8fa3f7ae9e307527c38822f6d
parent 155b8e26ce7e2228fb1e886fc97f0fd3c165a5c5

Fix Chameleon diags SFP TX bias calculation error
Early versions of the digital diagnostic standard (SFF-8472)
used a scale factor of 1uA/AD Count for interpreting laser
bias current readings. SFF-8472 later changed the scale
factor to 2uA/AD Count. I used an old spec when I coded up
the diags. Now we verified the SFP we used for Chameleon
complies with the latest SFF-8472. So I need to change the
formula.

Change-Id: I6e323ddd7d80a06a5ddc4ca197a254d36d2a734c

diags/chameleon/sfp.c

diff --git a/diags/chameleon/sfp.c b/diags/chameleon/sfp.c
index e17e02d..1974d27 100644
--- a/diags/chameleon/sfp.c
+++ b/diags/chameleon/sfp.c
@@ -175,7 +175,7 @@
     temp = value[0] + ((float)value[1]) / 256.0;
   }
   vcc = ((float)((value[2] << 8) + value[3])) / 10000.0;
-  tx_bias = ((float)((value[4] << 8) + value[5])) / 1000.0;
+  tx_bias = (((float)((value[4] << 8) + value[5])) * 2) / 1000.0;
   tx_power = ((float)((value[6] << 8) + value[7])) / 10000.0;
   rx_power = ((float)((value[8] << 8) + value[9])) / 10000.0;
   mod_curr = ((float)((value[12] << 8) + value[13])) / 1000.0;