linux-kernel - Re: [PATCH v2] i2c: stub: Add support for SMBus block commands

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Date:	Thu, 17 Jul 2014 15:21:35 +0200
From:	Wolfram Sang <wsa@...-dreams.de>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Randy Dunlap <rdunlap@...radead.org>,
	Jean Delvare <jdelvare@...e.de>, linux-i2c@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] i2c: stub: Add support for SMBus block commands

On Mon, Jul 07, 2014 at 07:23:03AM -0700, Guenter Roeck wrote:
> SMBus block commands are different to I2C block commands since
> the returned data is not normally accessible with byte or word
> commands on other command offsets. Add linked list of 'block'
> commands to support those commands.
> 
> Access mechanism is quite simple: Block commands must be written
> before they can be read. The first write selects the block length.
> Subsequent writes can be partial. Block read commands always return
> the number of bytes selected with the first write.
> 
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
> v2: Make new functionality only available on request via functionality
>     module parameter
>     Add more details about SMBus block mode support to documentation
>     Use correct sizeof() variable in devm_kzalloc
>     Use stub_find_block() only in SMBus block command itself.
>     Store first word of block data in chip->words[].
>     When writing block data and the written data is longer than
>     the first write, bail out with debug message indicating the reason
>     for the error.

Thanks for doing this and thanks to Jean for the thorough review.

The thing I miss is the documentation that SMBUS_BLOCK must explicitly
be activated and the description how to do it. A comment in the driver,
above STUB_FUNC_* defines might not hurt as well.

Also, I'd prefer to squash Jean's "increasing block length" patch into
this one if both of you are fine with that?

Regards,

   Wolfram


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