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hwmon: do not init sensors on startup

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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>
This commit is contained in:
Heiko Schocher 2011-08-01 04:01:43 +00:00 • committed by Wolfgang Denk
parent fb6440ee9b
commit 780f13a9e1
11 changed files with 28 additions and 149 deletions
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16
common/cmd_dtt.c
View file

@ -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);