Thread (9 messages) 9 messages, 3 authors, 2013-05-29

[I2C] informations + advice about messages handling

From: Mylene Josserand <hidden>
Date: 2013-05-29 10:25:09
Also in: kernelnewbies, linux-i2c, lkml

Hi Jean,

Le 24/05/2013 14:20, Jean Delvare a ?crit :
On Fri, 24 May 2013 11:52:54 +0200, Mylene Josserand wrote:
quoted
- an audio codec tlv320aic3204 : There is a driver for this device but
for some reasons, we did not use it. Did not find a "SMBus compliant" in
its datasheet.
The tlv320aic32x4 driver uses i2c_master_send, which is a shortcut to
i2c_transfer. However it seems to only send 2 bytes on the bus at once,
the same could be achieved with i2c_smbus_write_byte_data if needed.
Okay, thanks to have looked at it !
For completeness: a device might use transactions which are compliant
with SMBus without being formally "SMBus-compliant", because SMBus has
more constraints than just transaction types (I kept things simple
originally to not confuse you.) This may explain why it isn't mentioned
in the datasheet. Or just because the manufacturer did not care because
they target fully I2C-capable systems anyway.

What you have to look at is the transaction types. They are usually
described in the datasheet. Then compare with either the SMBus
specification or
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/i2c/smbus-protocol
and if they match then you can use the i2c_smbus_*() calls.

I have checked the PIC18F24201 according to your advice and, of what I 
have seen, it can handle the SMBus protocol.

Thank you for the explanation and trying to keep it simple for me :)


-- 
Myl?ne JOSSERAND
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