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| author | Heiko Schocher <hs@denx.de> | 2011-08-01 04:01:43 +0000 |
|---|---|---|
| committer | Wolfgang Denk <wd@denx.de> | 2011-08-04 23:30:38 +0200 |
| commit | 780f13a9e1a21098c6255aaa1c46ed80aa7a436c (patch) | |
| tree | 4273c1af78aa2f3079e11997e12814d66d47439e /common | |
| parent | fb6440ee9b110b759ef61fd80bbd0df1bbf0f37b (diff) | |
| download | u-boot-imx-780f13a9e1a21098c6255aaa1c46ed80aa7a436c.zip u-boot-imx-780f13a9e1a21098c6255aaa1c46ed80aa7a436c.tar.gz u-boot-imx-780f13a9e1a21098c6255aaa1c46ed80aa7a436c.tar.bz2 | |
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.c | 16 |
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); |