[Libdlo] some libdlo and DL-165 questions

Bernie Thompson bernie at plugable.com
Mon May 10 10:18:11 PDT 2010

Hi Matt,

On Mon, May 10, 2010 at 9:11 AM, Matt Barclay <mbarclay at gmail.com> wrote:

> 1.  Can I access the GPIOs on the DL-1x5 from user space?

Udlfb currently has no support for reading or writing GPIOs (from kernel or
user space). You'd have to add that to udlfb.

> 2.  What is the minimum resolution that the kernel framebuffer driver
> supports?  Can I drive 320x240?  I know, sounds strange, but I'm
> hoping one hardware design can scale from 2" LCD @ 240x320 up to 17" @
> 1600x1200

I'm not sure, actually.  I've only tested down to modes that standard
monitors can do (640x480).

I suspect they'll work, but note that for panels that don't report EDID,
you'll have to modify udlfb to set the specific timings you need (because
EDID reading is not 100% reliable, I've also thought for other reasons about
enhancing the udlfb's sysfs edid interface to allow a user mode entity to
supply a pre-canned edid -- if so, that would become another option that
wouldn't require actual per-mode hacks to udlfb)

Best wishes,
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