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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 <> 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 <> 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.


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