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authorHeiko Schocher <hs@denx.de>2011-08-01 04:01:43 +0000
committerWolfgang Denk <wd@denx.de>2011-08-04 23:30:38 +0200
commit780f13a9e1a21098c6255aaa1c46ed80aa7a436c (patch)
tree4273c1af78aa2f3079e11997e12814d66d47439e /common
parentfb6440ee9b110b759ef61fd80bbd0df1bbf0f37b (diff)
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hwmon: do not init sensors on startup
The U-Boot Design Principles[1] clearly say: Initialize devices only when they are needed within U-Boot, i.e. don't initialize the Ethernet interface(s) unless U-Boot performs a download over Ethernet; don't initialize any IDE or USB devices unless U-Boot actually tries to load files from these, etc. (and don't forget to shut down these devices after using them - otherwise nasty things may happen when you try to boot your OS). So, do not initialize and read the sensors on startup. Signed-off-by: Heiko Schocher <hs@denx.de> cc: Wolfgang Denk <wd@denx.de> cc: Holger Brunck <holger.brunck@keymile.com>
Diffstat (limited to 'common')
-rw-r--r--common/cmd_dtt.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/common/cmd_dtt.c b/common/cmd_dtt.c
index 3388e43..5bba12d 100644
--- a/common/cmd_dtt.c
+++ b/common/cmd_dtt.c
@@ -28,12 +28,16 @@
#include <dtt.h>
#include <i2c.h>
+static unsigned long sensor_initialized;
+
int do_dtt (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
{
int i;
unsigned char sensors[] = CONFIG_DTT_SENSORS;
int old_bus;
+ /* Force a compilation error, if there are more then 32 sensors */
+ BUILD_BUG_ON(sizeof(sensors) > 32);
/* switch to correct I2C bus */
old_bus = I2C_GET_BUS();
I2C_SET_BUS(CONFIG_SYS_DTT_BUS_NUM);
@@ -42,8 +46,16 @@ int do_dtt (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
* Loop through sensors, read
* temperature, and output it.
*/
- for (i = 0; i < sizeof (sensors); i++)
- printf ("DTT%d: %i C\n", i + 1, dtt_get_temp (sensors[i]));
+ for (i = 0; i < sizeof(sensors); i++) {
+ if ((sensor_initialized & (1 << i)) == 0) {
+ if (dtt_init_one(sensors[i]) != 0) {
+ printf("DTT%d: Failed init!\n", i);
+ continue;
+ }
+ sensor_initialized |= (1 << i);
+ }
+ printf("DTT%d: %i C\n", i + 1, dtt_get_temp(sensors[i]));
+ }
/* switch back to original I2C bus */
I2C_SET_BUS(old_bus);