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SubjectRe: [RFC 2.6.27 1/1] gpiolib: add support for batch set of pins
On Fri, Nov 28, 2008 at 4:01 AM, Sam Ravnborg <sam@ravnborg.org> wrote:
> On Wed, Nov 26, 2008 at 12:51:27AM -0500, Jaya Kumar wrote:
>> On Tue, Nov 25, 2008 at 11:15 PM, David Brownell <david-b@pacbell.net> wrote:
>> > On Tuesday 25 November 2008, Eric Miao wrote:
>> >> Using a bit mask will be more generic if the GPIOs are not contiguous.
>> >> Yet I still doubt this will be generic enough to be added to gpiolib.
>> >
>> > My expectation for this kind of mechanism was that systems who need
>> > to craft another parallel bus out of GPIO pins would be doing this
>> > with some system-specific utility functions.
>> >
>> > So my "is it generic enough" question is more at the level of "Are
>> > there enough Linux systems that need this sort of thing to justify
>> > generic support?". I happen not to have come across the need for
>> > such ganged access from Linux (yet). Whereas I've yet to use non-x86
>> > Linux systems that don't need to manipulate individual GPIO pins...
>>
>> I have come across the following scenarios where a bus set of gpio is useful:
>> - Broadsheet E-Ink controller (uses 16-bit data bus over GPIO)
>> framebuffer device (this patch is for this)
>> - Apollo/Hecuba E-Ink controller (uses 8-bit data bus over GPIO)
>> framebuffer device
>> - 8-bit parallel IO matrix LCD controllers, such as the Samsung KS108,
>> also Hitachi, etc
>
> We have such a system at work. And we need fast acces to the gpio pins
> when updating the LCD.
> I have not written/looked to deep at the code I just recall it was
> a bit messy and not something I would be proud of submitting to any ML.
>
> Sam
>

Okay. Please help me understand in case I misunderstood. Are you
saying the code that I posted is too messy? To me, actually I am proud
of it. :-) But if some parts look messy, I'm happy to work on
improving it. I will need some advice though and please advise me on
which parts look messy.

Thanks,
jaya


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