linux-kernel - Re: [I2C] informations + advice about messages handling

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Message-ID: <CA78C307B8F06747967D122FC656B15398645D@SERVEUR0.nvp.local>
Date:	Wed, 29 May 2013 12:17:58 +0200
From:	"Mylene Josserand" <Mylene.Josserand@...ocap.com>
To:	"Jean Delvare" <khali@...ux-fr.org>
Cc:	"anish singh" <anish198519851985@...il.com>,
	"kernelnewbies" <kernelnewbies@...nelnewbies.org>,
	"Linux I2C" <linux-i2c@...r.kernel.org>,
	"linux-kernel-mail" <linux-kernel@...r.kernel.org>,
	"Arnd Bergmann" <arnd@...db.de>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [I2C] informations + advice about messages handling

Hi Jean,

Le 24/05/2013 14:20, Jean Delvare a écrit :
> On Fri, 24 May 2013 11:52:54 +0200, Mylene Josserand wrote:
>> - 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 :)


-- 
Mylène JOSSERAND
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