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    SubjectRe: [RFC 2.6.27 1/1] gpiolib: add support for batch set of pins
    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


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