Re: Creator3D resolution switching

On Sun, 25 Mar 2018 22:36:21 +0100
Sad Clouds <[email protected]> wrote:

> On Sun, 25 Mar 2018 22:02:05 +0100
> Julian Coleman <[email protected]> wrote:
> 
> > Hi,
> > 
> > > Hi, I'm having some issues with Creator3D graphics card and
> > > NetBSD-8. On boot, NetBSD automatically switches resolution, but
> > > this results in a blank screen with my monitor.
> > 
> > The ffb driver reads the EDID data and should switch to a mode that
> > is supported by the monitor ...
> > 
> > > I have Dell 1920x1200 monitor, but it doesn't have a VGA port, so
> > > I'm using VGA-to-HDMI converter http://www.avaccess.com/c160.html
> > 
> > ... so I wonder which mode is chosen here.
> > 
> > > When in OpenBoot, everything is displayed correctly, but as soon
> > > as NetBSD boots, I get a blank screen, i.e. no output to monitor.
> > 
> > What resolution/timing does OFW choose?
> > 
> > > Is there a way to stop NetBSD from switching resolution, or is
> > > there a NetBSD specific ffb command line tool to manually reset
> > > resolution from a startup script?
> > 
> > You can force the resolution using the `output-device' field, for
> > example:
> > 
> >   setenv output-device screen:r1280x1024x60
> > 
> > (or set it using `eeprom`).
> > 
> > It would be interesting to see the output from a kernel compiled
> > with FFB_DEBUG.  However, because the monitor doesn't handle the
> > mode we choose, commenting out all the calls to DAC_WRITE() would
> > show the debugging but not change video mode.  See:
> > 
> >   https://nxr.netbsd.org/xref/src/sys/arch/sparc64/dev/ffb.c#1596
> > 
> > Regards,
> > 
> > Julian
> 
> Hello, yes I can use "setenv output-device ..." to set various
> resolutions, the problem happens when NetBSD boots and resets that
> resolution to something else, and screen goes blank. It would be nice
> to have some command line tool to control ffb, similar to Solaris
> fbconfig. Maybe I'll look into writing one.
> 
> I'll follow your suggestion, enable FFB_DEBUG and comment out
> DAC_WRITE calls.
> 
> It also makes me wonder, Creator3D can support max resolution of
> 1600x1200, but my monitor is 1920x1200, is it possible that
> sparc64/dev/ffb.c tries to force graphics card into 1920x1200 which it
> can't support and it just gives up?

I had a look at the spec and looks like this model of Creator3D can
handle up to 1920x1200. Also looking at dmesg I can see NetBSD setting
resolution to 1920x1080, which should be supported:

ffb0 at mainbus0 addr 0xfebee000: Creator3D, model SUNW,501-4788, dac 10
ffb0: video mode set to 1920 x 1080 @ 60Hz
ffb0: attached to /dev/fb0

Maybe the VGA converter is buggy.