linux-kernel - Re: [PATCH v2] Bitbanging i2c bus driver using the GPIO API

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Date:	Sat, 10 Mar 2007 20:02:20 -0800
From:	David Brownell <david-b@...bell.net>
To:	Haavard Skinnemoen <hskinnemoen@...el.com>
Cc:	Jean Delvare <khali@...ux-fr.org>, Bryan Wu <bryan.wu@...log.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Deepak Saxena <dsaxena@...xity.net>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] Bitbanging i2c bus driver using the GPIO API

On Saturday 10 March 2007 5:13 am, Haavard Skinnemoen wrote:
> This is a very simple bitbanging i2c bus driver utilizing the new
> arch-neutral GPIO API. ...
> ---
> This patch is different from the first patch in the following ways:
>   * Handles pins set up as open drain (aka multidrive) by toggling
>     the output value instead of the direction
>   * Handles output-only SCL pins the same way, and also does not
>     install a getscl() callback for such pins
>   * Does not add anything to include/linux/i2c-ids.h
>   * Sets the output value explicitly after changing the direction to
>     output.
>   * Plugs a memory leak in remove() -- algo_data wasn't freed.
>   * Prints out the pin IDs in decimal, with an extra note when clock
>     stretching isn't supported
> 
> This version has been compile-tested only. I'll give it a spin when I
> get back to work on monday.
> 
> Dave, does this address your concerns?

Yes, though see my followup to Jean's note.  Unless I make time
to test this out on some system, the issues seem to be:

 (a) will need to change once gpio_direction_output() gains
     that second argument;

 (b) i2c-gpio.h could stand one minor comment addition to highlight
     an assumption.

Looking good!

- Dave
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