linux-kernel - Re: Latest gpio gumph

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Date:	Wed, 28 May 2008 10:14:25 +0200
From:	Haavard Skinnemoen <haavard.skinnemoen@...el.com>
To:	David Brownell <david-b@...bell.net>
Cc:	Ben Nizette <bn@...sdigital.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	kernel@...32linux.org
Subject: Re: Latest gpio gumph

David Brownell <david-b@...bell.net> wrote:
>   - an avr32 patch, appended (no response on the avr32 list)

Sorry about the lack of response.

I'm not all that enthusiastic about this patch though...

> From: David Brownell <dbrownell@...rs.sourceforge.net>
> Subject: AVR32: minor GPIO handling updates
> 
>  * gpio_direction_output() should disable the pullups just like
>    at32_select_gpio(... AT32_GPIOF_OUTPUT) does, for consistency
>    between those alternative initialization paths.

But then we need to keep track of whether pullups used to be enabled so
that we can re-enable it in gpio_direction_input(), don't we?

I can't see the harm of keeping the pullup enabled while the port is
configured as output. For consistency, I'd rather honor the pullup flag
in at32_select_gpio() regardless of AT32_GPIOF_OUTPUT.

>  * On the odd chance some code uses a pin as a GPIO IRQ without
>    calling gpio_request() or gpio_direction_input(), the debug
>    dump should still show its pin status.

Hmm. I guess that makes sense, though I would be lying if I said I care
all that much. I think gpiolib is going pretty far to accommodate buggy
drivers that don't call gpio_request() as it is.

Haavard
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