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authorJean Delvare <khali@linux-fr.org>2007-10-13 23:56:31 +0200
committerJean Delvare <khali@hyperion.delvare>2007-10-13 23:56:31 +0200
commit553515e5c54dbf3340cd6773aaf0acb53291d6ad (patch)
tree604b27ffd6452b925c4f2433e55fec60f755e44b /Documentation
parent95a7f10eadcd88cfd6640e44c7b8cf9ac1afafe7 (diff)
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')
-rw-r--r--Documentation/i2c/chips/pcf85748
1 files changed, 3 insertions, 5 deletions
diff --git a/Documentation/i2c/chips/pcf8574 b/Documentation/i2c/chips/pcf8574
index 2752c8ce316..5c1ad1376b6 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.