linux-kernel - Re: [PATCH] ARM: Kirkwood: fix unused mvsdio gpio pins

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Date:	Sat, 23 Mar 2013 16:17:44 +0100
From:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
To:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
Cc:	Andrew Lunn <andrew@...n.ch>,
	Russell King <linux@....linux.org.uk>,
	Jason Cooper <jason@...edaemon.net>,
	linux-kernel@...r.kernel.org, Soeren Moch <smoch@....de>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] ARM: Kirkwood: fix unused mvsdio gpio pins

Dear Sebastian Hesselbarth,

On Sat, 23 Mar 2013 13:56:58 +0100, Sebastian Hesselbarth wrote:
> mvsdio_platform_data allows to pass card detect and write protect gpio
> numbers to the driver. Some kirkwood boards don't use both pins as
> they are not connected, and don't set the corresponding value in
> platform_data.
> 
> This will leave the unset values in platform_data initialized as 0,
> which is in fact a valid gpio pin. mvsdio will grab that pin and
> configure it as gpio, which in turn breaks nand controller as mpp0
> also carries nand_io2.
> 
> This patch fixes the above by initializing unused gpio functions in
> the platform_data with an invalid (-1) value.
> 
> Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
> Reported-by: Soeren Moch <smoch@....de>

This somewhat "conflicts" with the patch I've submitted on the mvsdio
driver to exclude 0 as a valid GPIO, see
http://lists.infradead.org/pipermail/linux-arm-kernel/2013-March/157157.html.
This patch ensures that the mvsdio driver behaves as it was behaving
before 3.9 as far as legacy probing is concerned.

That said, I have nothing against explicitly setting those GPIO values
to an invalid value. Maybe -EINVAL would make more sense than just -1 ?

Best regards,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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