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

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Date:	Mon, 12 Mar 2007 16:11:09 +0100
From:	Jean Delvare <khali@...ux-fr.org>
To:	Haavard Skinnemoen <hskinnemoen@...el.com>
Cc:	bryan.wu@...log.com, David Brownell <david-b@...bell.net>,
	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

Hi Haavard,

On Mon, 12 Mar 2007 15:53:59 +0100, Haavard Skinnemoen wrote:
> On Mon, 12 Mar 2007 15:34:57 +0100
> Haavard Skinnemoen <hskinnemoen@...el.com> wrote:
> 
> > > > +	bit_data->udelay	= 5,			/* 100 kHz */
> > > > +	bit_data->timeout	= HZ / 10,		/* 100 ms */  
> > > 
> > > Can we add these udelay/timeout to struct i2c_gpio_platform_data? And
> > > let customer to choose these according their specific requirement. We
> > > use Kconfig to do this, but Jean and David don't like the idea, -:(  
> > 
> > Yeah, they need to be a bit more configurable than they currently are.
> > And I think it makes sense to pass them from the board setup code, since
> > this is where things depending on board-specific details (signal quality
> > issues, pullup resistor values, etc.) are supposed to go.
> 
> By the way, timeout seems to be hardcoded to 100 jiffies in the
> i2c-algo-bit driver, so there's probably not much point passing it from
> the board code when it's going to be overridden anyway. I'll add just a
> udelay parameter to the platform struct for  now.

No, it's not hardcoded. I know it looks confusing. struct i2c_adapter
has a timeout field, that's the one being set to 100 in i2c-algo-bit,
but i2c-algo-bit uses the i2c_algo_bit_data timeout field. The
i2c_adapter timeout field is unused.

This is clearly calling for a cleanup but I don't have time for this
right now.

-- 
Jean Delvare
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