Jean emailed me saying he didn't want to be CCed. On Sun, Nov 30, 2008 at 6:48 AM, David Brownell <david-b@xxxxxxxxxxx> wrote: > On Thursday 27 November 2008, Sam Ravnborg wrote: >> > > 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 > > All of those can also be handled with traditional parallel data > busses too, of course. Are you saying you've seen these used > with Linux systems? Enough to justify generic support? Assuming I've understood you correctly about generic support, yes. I used the 3 above with Linux arm systems that were interfaced to them via gpio. The matrix displays had just 128x64 so the 8x gpio_set_value penalty wasn't a biggie. The E-Ink displays range from 800x600 to 1200x826 so the 16x gpio_set_value became a bottleneck. In terms of generic support, the Broadsheet display controller is also used on i.MX31 and SC2410/2440 boards so those platform drivers (assuming those good folks submit them, (i've only written and submitted am300epd.c)) should also benefit. Thanks, jaya -- 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
