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@xxxxxxxxxxx> 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 -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
