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authorAnton Arapov <anton@redhat.com>2012-08-07 11:21:50 +0200
committerAnton Arapov <anton@redhat.com>2012-08-07 12:52:25 +0200
commit1d44b6f3fcf6058fb7c960b7558766967e8028f7 (patch)
tree53d88547c973ba048d233091a3f91f3173ad01df /Documentation/i2c/i2c-protocol
parentd91eda5d7b0383e6a0c83e0146ff141ff3b1355b (diff)
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Signed-off-by: Anton Arapov <anton@redhat.com>
Diffstat (limited to 'Documentation/i2c/i2c-protocol')
-rw-r--r--Documentation/i2c/i2c-protocol9
1 files changed, 8 insertions, 1 deletions
diff --git a/Documentation/i2c/i2c-protocol b/Documentation/i2c/i2c-protocol
index 10518dd5881..0b3e62d1f77 100644
--- a/Documentation/i2c/i2c-protocol
+++ b/Documentation/i2c/i2c-protocol
@@ -49,7 +49,9 @@ a byte read, followed by a byte write:
Modified transactions
=====================
-We have found some I2C devices that needs the following modifications:
+The following modifications to the I2C protocol can also be generated,
+with the exception of I2C_M_NOSTART these are usually only needed to
+work around device issues:
Flag I2C_M_NOSTART:
In a combined transaction, no 'S Addr Wr/Rd [A]' is generated at some
@@ -60,6 +62,11 @@ We have found some I2C devices that needs the following modifications:
we do not generate Addr, but we do generate the startbit S. This will
probably confuse all other clients on your bus, so don't try this.
+ This is often used to gather transmits from multiple data buffers in
+ system memory into something that appears as a single transfer to the
+ I2C device but may also be used between direction changes by some
+ rare devices.
+
Flags I2C_M_REV_DIR_ADDR
This toggles the Rd/Wr flag. That is, if you want to do a write, but
need to emit an Rd instead of a Wr, or vice versa, you set this