[Libdlo] what displaylink device should i buy and what steps are still needed?

[Bernie Thompson]

On Fri, Jul 2, 2010 at 3:07 AM, Jelle de Jong <jelledejong at powercraft.nl> wrote:
> Why is does udlfb detect 1600x1200 as the highest valid mode. Would an
> DL-195 nog go higher, or is this the higest VESA mode or something?

The pixel limit match of yours matches a DL-195.  The reason 1600x1200
is highest, is all the VESA modes precalculated in the kernel are not
widescreen: http://lxr.linux.no/#linux+v2.6.32/drivers/video/modedb.c#L279
 udlfb does not currently call fb_find_mode, which accesses the larger
private precalculated table above that that has a bit more.

> If I set the framebuffer to 1600x1200 i can play a bit with the fbset and
> change resolutions. I just can't figure out if the used timings are correct
> and if udlfb is playing all-long correctly?

It looks like it is.  Your widescreen monitor may just not like these
modes (or they're too high).

> Is there a way to but my HEX EDID detected by the intel driver in some sort
> of array in udlfb.c? Somebody fancy to make an example patch?
>
> (II) intel(0): EDID (in hex):
> (II) intel(0):  00ffffffffffff004c2d250239314148
> (II) intel(0):  211001030e291a878ad7a5a2594a9624
> (II) intel(0):  145054bfef809500950f81808140714f
> (II) intel(0):  0101010101019a29a0d0518422305098
> (II) intel(0):  36009a011100001c000000fd00384b1e
> (II) intel(0):  510e000a202020202020000000fc0053
> (II) intel(0):  796e634d61737465720a2020000000ff
> (II) intel(0):  004853484c3831323030330a202000be

A writable sysfs edid file is probably the best way to handle this,
rather than patching code.  I know others (who are working on embedded
systems with fixed screens & no edid) would like this.  But it would
require laying down a udev rule to write the edid every time your
device shows up -- not terrible, but as you say, it's not really a
solution for normal users.

So really the thing is to get a good EDID readback of the preferred
mode and timings of monitor, so things just work.  Everything else is
a bit of a hack.  So really best to wait for those new adapters.

> Does the VLC mediaplayer work correctly with the fbdev based xorg desktop?

Yes, for X11 output. But if you mean to run directly to fb, you'll
need defio support enabled in the udlfb code (to notify of framebuffer
changes based on page faults).  Defio still has issues, however (see
other threads on this list).

Best wishes,
Bernie