[U-Boot-Users] Bug in DTT for temperatures below zero degress !!!
Steven Scholz
steven.scholz at imc-berlin.de
Wed Jun 15 10:50:27 CEST 2005
Hi there,
there's a terrible bug in the current U-Boot CVS concerning DDT:
For temperature below zero the function dtt_get_temp() (at least for lm75)
returns wrong values!
...
DTT: 1 is 235 C
LCD: Hitachi TX14D11 5,7" 320x240 TFT (235°C)
WDT: disabled
This is because of the use of an "int" although the lm75 only returns two
byte ("signed short").
This trivial fix is needed:
Index: u-boot/dtt/lm75.c
===================================================================
RCS file: /cvsroot/u-boot/u-boot/dtt/lm75.c,v
retrieving revision 1.2
diff -u -r1.2 lm75.c
--- u-boot/dtt/lm75.c 27 Jun 2003 21:32:38 -0000 1.2
+++ u-boot/dtt/lm75.c 15 Jun 2005 08:44:21 -0000
@@ -174,7 +170,7 @@
int dtt_get_temp(int sensor)
{
- return (dtt_read(sensor, DTT_READ_TEMP) / 256);
+ return ( ((signed short) dtt_read(sensor, DTT_READ_TEMP)) / 256);
} /* dtt_get_temp() */
#endif /* CONFIG_DTT_LM75 */
Then the output is correct:
...
DTT: 1 is -28 C
LCD: Hitachi TX14D11 5,7" 320x240 TFT (-28°C)
CCFL: disabled (too cold!)
WDT: disabled
I am afraid this is an issues on all DTT in U-Boot. Some even only use "uchar".
Comments?
--
Steven
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