Xfbdev fails with "no screens found"

Thu Apr 14 00:04:30 PDT 2011

On 14/04/2011 4:28 PM, zt.tmzt at gmail.com wrote:
>
> On Apr 13, 2011 10:29 PM, "Dushara Jayasinghe"
> <dushara.jayasinghe at hydrix.com <mailto:dushara.jayasinghe at hydrix.com>>
> wrote:
>  >
>  > Hi Thanks for the reply.
>  >
>  > Somehow I stuffed up the post with all the relevant info. I've pasted
> it here again:
>  >
>  > ----------------------------------- >8
> ----------------------------------------
>  > DISPLAY wasn't the issue. To cut a long story short... I needed to
> update some stuff on buildroot.
>  >
>  > However, it's still not working properly. I had to add the attached
> patch to get it to work with the frame buffer device I'm using. Xfbdev
> runs fine now but when I execute xlogo, nothing is displayed on the
> screen. The part of the screen gets 'cleared' so I know that it writes
> something to /dev/fb0.
>  >
>  > The output of fbset -i:
>  >
>  > # fbset -i
>  >
>  > mode "240x128-158"
>  > # D: 5.000 MHz, H: 20.325 kHz, V: 157.560 Hz
>  > geometry 240 128 240 128 1
>  > timings 200000 3 1 0 0 2 1
>  > rgba 0/0,0/0,0/0,0/0
>  > endmode
>  >
>  > Frame buffer device information:
>  > Name : DISP0 BG
>  > Address : 0x906b8000
>  > Size : 4096
>  > Type : PACKED PIXELS
>  > Visual : MONO01
>  > XPanStep : 1
>  > YPanStep : 1
>  > YWrapStep : 0
>  > LineLength : 32
>  > Accelerator : No
>  > #
>  >
>  > ----------------------------------- >8
> ----------------------------------------
>  >
>  > I'm using Xfbdev because, this is for an embedded product and I want
> to keep things as small as possible.
>  >
>  > The framebuffer driver I'm using is for a monochrome LCD panel
> running on an iMX.25 based system (I tweaked the driver supplied by
> Freescale to suite our needs.
>  >
>  > Thanks.
>  > Dushara
>  >
>  > P.S. What is preferred on this ML top/bottom posts?
>  >
>  >
>  > On 14/04/2011 12:03 PM, zt.tmzt at gmail.com <mailto:zt.tmzt at gmail.com>
> wrote:
>  >>
>  >>
>  >> Hi.
>  >> Could you explain in more detail what you are trying to do, include
> the output of fbset on your hardware and what framebuffer driver you are
> using?
>  >>
>  >> Xfbdev is not a nested server, don't see how setting DISPLAY would help.
>  >>
>  >> If you can, please strace Xfbdev and include that as well. I assume
> an IOCTL is failing though I don't see any detailed logs. Xfbdev is
> based on the kdrive X server, it doesn't have the same configuration or
> logging as Xorg servers do. Why do you need to use Xfbdev, does Xorg
> (fbdev driver) not work?
>  >>
>  >> Thanks,
>  >> Timothy Meade
>  >> tmzt on #xorg and #xorg-users
>  >>
>  >> On Apr 13, 2011 7:50 PM, "Dushara Jayasinghe"
> <dushara.jayasinghe at hydrix.com <mailto:dushara.jayasinghe at hydrix.com>>
> wrote:
>  >> >
>  >> > Sorry reposting this coz I stuffed up the subject...
>  >> >
>  >> > On 13/04/2011 4:34 PM, Dushara Jayasinghe wrote:
>  >> >>
>  >> >>  On 12/04/2011 11:06 AM, xorg-devel-request at lists.x.org
> <mailto:xorg-devel-request at lists.x.org> wrote:
>  >> >>>
>  >> >>> Date: Mon, 11 Apr 2011 21:55:27 +0200
>  >> >>> From: Abdoulaye Walsimou GAYE<awg at embtoolkit.org
> <mailto:awg at embtoolkit.org>>
>  >> >>> Subject: Re: Xfbdev fails with "no screens found"
>  >> >>> To: xorg-devel at lists.x.org <mailto:xorg-devel at lists.x.org>
>  >> >>> Message-ID:<4DA35CAF.1090708 at embtoolkit.org
> <mailto:4DA35CAF.1090708 at embtoolkit.org>>
>  >> >>> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
>  >> >>>
>  >> >>> On 04/11/2011 10:01 AM, Dushara Jayasinghe wrote:
>  >> >>>>
>  >> >>>> Hi all,
>  >> >>>>
>  >> >>>> I'm trying to use Xfbdev on an embedded linux device with a
> monochrom LCD display. However, the command returns the following error:
>  >> >>>>
>  >> >>>> Fatal server error:
>  >> >>>> no screens found
>  >> >>>>
>  >> >>>> Using xserver_xorg-server-1.7.5
>  >> >>>> with kdrive/fbdev
>  >> >>>
>  >> >>> Hello,
>  >> >>> does the following command line, before starting Xfbdev, fixes
> the issue:
>  >> >>> export DISPLAY=:0
>  >> >>>
>  >> >>>
>  >> >>>
>  >> >>> _______________________________________________
>  >> >>> xorg-devel at lists.x.org <mailto:xorg-devel at lists.x.org>: X.Org
> development
>  >> >>> Archives: http://lists.x.org/archives/xorg-devel
>  >> >>> Info: http://lists.x.org/mailman/listinfo/xorg-devel
>  >> >
>  >> >
>  >> > --
>  >> > Dushara Jayasinghe | Senior Software Engineer
>  >> > dushara.jayasinghe at hydrix.com
> <mailto:dushara.jayasinghe at hydrix.com> | +61 3 8573 5221
>  >> > Hydrix: Our Expertise – Your Competitive Advantage
>  >> > www.hydrix.com <http://www.hydrix.com> | fax +61 3 9572 2686 |
> phone +61 3 8573 5299
>  >> >
>  >> > _______________________________________________
>  >> > xorg-devel at lists.x.org <mailto:xorg-devel at lists.x.org>: X.Org
> development
>  >> > Archives: http://lists.x.org/archives/xorg-devel
>  >> > Info: http://lists.x.org/mailman/listinfo/xorg-devel
>  >
>  >
>  > --
>  > Dushara Jayasinghe | Senior Software Engineer
>  > dushara.jayasinghe at hydrix.com <mailto:dushara.jayasinghe at hydrix.com>
> | +61 3 8573 5221
>  > Hydrix: Our Expertise – Your Competitive Advantage
>  > www.hydrix.com <http://www.hydrix.com> | fax +61 3 9572 2686 | phone
> +61 3 8573 5299
>
> I believe bottom, I couldn't figure out which of the quoted messages to
> reply to.
>
> I don't believe the visual is getting setup right, I'm pretty sure this
> going to need changes to the server though Keith or someone else on the
> list might know for sure. You might do better with overlay support, or
> something that supports a single bit depth. I also wonder if the rgba
> mask has anything to do with it. I haven't looked at this code recently,
> but I'm pretty sure it's using MI/FB to create a visual from the FBIO
> fixed structure. You can try -screen parameter if you can figure out the
> right one, but it will probably still try to set the config back to the
> fbdev and fail. If somebody knows how to create a monochrome visual/root
> pixmap you could modify the server to do that, or properly support the
> visual flags in your fbset output.
>
> --
> Timothy Meade
> tmzt on #xorg-devel on freenode
>
>
>
> _______________________________________________
> xorg-devel at lists.x.org: X.Org development
> Archives: http://lists.x.org/archives/xorg-devel
> Info: http://lists.x.org/mailman/listinfo/xorg-devel

Not sure what overlay support is. Have you got any references I can 
follow up on?

I wondered about the rgba mask too but according to the man pages - 
fb.modes - it's only relevent for truecolor.

What is MI/FB?

Do you think my patch is on the right track? (i.e. adding support to 
FB_VISUAL_MONOxx) ?

Thanks again.

Dushara