linux-kernel - Re: [PATCH 1/2] gpio: gpio-generic: Fix bug in big endian bit conversion

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Message-ID: <512CA7D9.3040004@gaisler.com>
Date:	Tue, 26 Feb 2013 13:17:29 +0100
From:	Andreas Larsson <andreas@...sler.com>
To:	Grant Likely <grant.likely@...retlab.ca>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	Rob Herring <rob.herring@...xeda.com>,
	linux-kernel@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	software@...sler.com
Subject: Re: [PATCH 1/2] gpio: gpio-generic: Fix bug in big endian bit conversion

On 2013-02-26 11:46, Andreas Larsson wrote:
> On 2013-02-26 08:52, Grant Likely wrote:
>> On Sat, 09 Feb 2013 14:58:55 +0000, Grant Likely
>> <grant.likely@...retlab.ca> wrote:
>> We /could/ have a ioread32be/write32be mode in the driver, but I don't
>> think that is the right approach. It means we need yet another set of
>> accessors for register except using the 'be' variants. Blech. What I'd
>> actually like to do is add a bitmask field to the gpio_desc which can be
>> calculated ahead of time to whatever madness is required from the way
>> the device is wired. Then the access routines don't need to even care.
>> they just apply the bitmask to ioread/iowrite and it doesn't even need
>> to know what the bit number actually is. The new support for gpio_desc
>> in the core code makes this feasable.
>
> I am not sure I understand what you mean here or what new support for
> gpio_desc you are referring to (looking in gpio/next at
> git://git.secretlab.ca/git/linux-2.6).
>
> Do you mean to add something like an 'unsigned long bitmask[64]' bitmap
> array with one bitmap for each gpio line to struct gpio_desc and use
> this primarily by gpio-generic.c, populated in bgpio_init? Is gpio_desc
> now available outside of gpiolib.c in some repository/branch that I
> might be unaware of?

Ah, I realize that it is the "gpiolib: remove gpio_desc[] static array" 
patch series you refer to, not yet pushed to gpio/next at 
git://git.secretlab.ca/git/linux-2.6.

The question on how you intend the bitmap field to be 
defined/used/populated remains.

Cheers,
Andreas

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