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| author | Jean Delvare <khali@linux-fr.org> | 2007-10-13 23:56:31 +0200 |
|---|---|---|
| committer | Jean Delvare <khali@hyperion.delvare> | 2007-10-13 23:56:31 +0200 |
| commit | 553515e5c54dbf3340cd6773aaf0acb53291d6ad (patch) | |
| tree | 604b27ffd6452b925c4f2433e55fec60f755e44b /Documentation/i2c/chips/pcf8574 | |
| parent | 95a7f10eadcd88cfd6640e44c7b8cf9ac1afafe7 (diff) | |
| download | lwn-553515e5c54dbf3340cd6773aaf0acb53291d6ad.tar.gz lwn-553515e5c54dbf3340cd6773aaf0acb53291d6ad.zip | |
i2c/pcf8574: No arbitrary initialization
Do not initialize the PCF8574 with an arbitrary value. Users will have
to write the initial value to sysfs themselves.
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Aurelien Jarno <aurelien@aurel32.net>
Diffstat (limited to 'Documentation/i2c/chips/pcf8574')
| -rw-r--r-- | Documentation/i2c/chips/pcf8574 | 8 |
1 files changed, 3 insertions, 5 deletions
diff --git a/Documentation/i2c/chips/pcf8574 b/Documentation/i2c/chips/pcf8574 index 2752c8ce3167..5c1ad1376b62 100644 --- a/Documentation/i2c/chips/pcf8574 +++ b/Documentation/i2c/chips/pcf8574 @@ -62,8 +62,6 @@ if the corresponding output is set as 1, otherwise the current output value, that is to say 0. The write file is read/write. Writing a value outputs it on the I/O -port. Reading returns the last written value. - -On module initialization the chip is configured as eight inputs (all -outputs to 1), so you can connect any circuit to the PCF8574(A) without -being afraid of short-circuit. +port. Reading returns the last written value. As it is not possible +to read this value from the chip, you need to write at least once to +this file before you can read back from it. |