linux-kernel - Re: Frame buffers and early i2c

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Date:	Mon, 9 Jun 2008 20:52:12 +0200
From:	Jean Delvare <khali@...ux-fr.org>
To:	Uli Luckas <u.luckas@...d.de>
Cc:	linux-kernel@...r.kernel.org, adaplas@...il.com,
	Linux I2C <i2c@...sensors.org>
Subject: Re: Frame buffers and early i2c

On Mon, 9 Jun 2008 16:47:42 +0200, Uli Luckas wrote:
> I am in the process of trying out a display connected to a colibri board's 
> pxa frame buffer device. The display's power supply is switch through i2c.
> 
> In order to use the frame buffer console I have i2c and pxafb compiled in.
> 
> By default, the pxafb driver get's initialized before the i2c bus causing the 
> display power up to fail.
> 
> What do i2c people think about changing the link order here?

Why don't you ask on the i2c mailing list? Cc added.

Personally I have no objection, but dependencies can be tricky so
you'll have to be careful. video is early in the link order at the
moment.

> What do other frame buffer drivers handle the absence of i2c during early 
> boot?

Interestingly enough, they appear to do fine, despite the linking
order. Maybe because i2c_init is a subsys_initcall() while framebuffer
drivers are initialized with module_init()? Then I'm not sure why your
own driver has a problem there.

-- 
Jean Delvare
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