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GLP1.6.x: Using a second display with X11

Steve Schefter
Expert 1780 points

Hi.

drivers/gpu/drm registers a single framebuffer, so there is just /dev/fb0.

drivers/staging/omapdrm creates several framebuffers, but does not register them so there is no corresponding /dev/fbN device.

Therefore, how can I set up a second screen in the in the xorg.conf file in order to use two displays?

Regards,

    Steve

  • 0
    TI__Intellectual 2505 points

    Steve,

    Could you please specify what is your use case? Are you trying to have one screen on HDMI connector and one on DVI connector at the same time on Panda?

    I will come back with a sample xorg.conf that sets up 2 displays.

    Regards,

    Magdalena

  • 0 in reply to Magdalena Iovescu
    Expert 1780 points

    Hi Magdalena.

    I wish to use DVI and LCD2.

    Thanks,

        Steve

  • 0 in reply to Steve Schefter
    TI__Intellectual 2505 points

    Hello Steve,

    Please find attached a sample xorg.conf file that sets up 2 displays: http://e2e.ti.com/cfs-file.ashx/__key/communityserver-discussions-components-files/849/3175.xorg.conf. The important 'Option's to note are rotation, "LeftOf", "RightOf", "Primary".

    Looking forward to hearing your results.

    Regards,

    Magdalena

  • 0 in reply to Magdalena Iovescu
    Expert 1780 points

    Thanks Magdalena.

    However, the xorg.conf doesn't look like it is for a pandaboard with omapdrm.  Under the Device section, it lists radeon as the driver.

    This is the main section I'm looking for.  Going back to my original question, I'm wondering how you specify the different display devices.  They can't be distinguished with a different framebuffer device, for example.

    Regards,

       Steve

  • 0 in reply to Steve Schefter
    TI__Intellectual 2505 points

    Steve,

    You are correct, this is for a ubuntu PC. I will investigate more to see whether someone inside TI has this working on panda and will get back shortly.

    Regards,

    Magdalena

  • 0 in reply to Magdalena Iovescu
    TI__Intellectual 1300 points

    Steve,

    Have you gotten all the help you need for this question?

  • 0 in reply to Matthew Kiser
    Expert 1780 points

    Hi Matt.

    No, the question was never answered.

        Steve

  • 0 in reply to Steve Schefter
    TI__Intellectual 1300 points

    So, if understand correctly, you want to run GLP 1.6 with two monitors on a panda board?

  • 0 in reply to Matthew Kiser
    Expert 1780 points

    Hi Matt.

    That's correct.  But specifically, I want to use X11.  So that means omapdrm, etc and not just a raw omap framebuffer. 

    So the key to the question is: how do you specify the different devices/displays in xorg.conf since you can't use the traditional /dev/fb0 /dev/fb1?  With omapdrm, you get just one framebuffer.

  • 0 in reply to Steve Schefter
    TI__Intellectual 1300 points

    Steve,

    The answer I am getting is that xrandr will work with two monitors and omapdrm on x11. So you would run xrandr to configure two displays as normal. This presumes you have two working displays, I don't know what hardware you are using, or how they are configured. But all displays are managed with a single device file and multiple displays are going to be configured with normal xrandr commands.

  • 0 in reply to Matthew Kiser
    Expert 1780 points

    Hi Matt.

    While it is true that the devices are managed by xrandr, that doesn't really answer the question about how they are configured in xorg.conf.  The X11 server still needs to know about the devices and that means that they need to be configured in xorg.conf.  It needs to know, for example, that you have two displays and how they are placed in a virtual.

    I have attached the xorg.conf which does this in case anyone else seeing this question is attempting to do the same.

    Regards,

        Steve

  • 0 in reply to Steve Schefter
    Expert 1285 points

    Hi Steve,

    Were you able to achieve the two display using X11 and omapdrm/dss? as I intent to do the same, could you please

    list the steps or elaborate on how did you do it?

    Thanks & Regards,

    Viks

  • 0 in reply to vikash patil
    Expert 1780 points

    Hi Viks.

    Dual display is supported in the Phytec OMAP4 BSP version 12.2.0.  You can obtain it at:
    http://www.phytec.com/wiki/index.php/PhyCORE-OMAP44xx_Linux_BSP-PD12.2.0

    Take a look at the notes in the /etc/xorg.conf file which tell you how to configure X11 for dual display.  Basically, you have a single frame buffer (virtual display) equivalent to the size of your physical displays set side-by-side.  You then tell the application to put its output within the large frame buffer such that it will end up on the correct display.  For example, with sample OpenGL ES applications, you add "posy=<value>".

    Regards,

        Steve

  • 0 in reply to Steve Schefter
    Expert 1285 points

    Hi Steve,

    Thanks for your quick explanation. So this is a extended mode type of dual display configuration. Is there any other modification required apart from xorg-conf file?

    Regards,

    Viks

  • 0 in reply to vikash patil
    Expert 1780 points

    Hi Viks.

    The xorg.conf file is the key.  You need to have an omap drivers for X11 (omap_drv.so) which includes support for RandR.  However, TI's recent releases have that.

    TI's OMAP4 BSP is a Ubuntu BSP.  In the case of the Phytec BSP, it is based on ptxdist and gives you a more traditional BSP.  That is, building all but the proprietary packages from source rather than using TI-provided .deb binary packages.  You will either need to stick with TI's Ubuntu packages or obtain the source from TI under NDA.

    Regards,
        Steve

  • 0 in reply to Steve Schefter
    Expert 1285 points

    Hi Steve,

    I want to achieve this dual display using OMAP5 or JACINTO6 on customized platform with linux having X11/Wayland/drm graphics backend. Required sources I can ask for TI, off course under NDA.

    - One method as you mentioned configuring in Extended mode.

    As a other possibility I am thinking of using two different XServers or Wayland instances to control two independent displays/connectors of the same card. However I am not sure what all modification and configuration are required if this is possible?

    Regards,

    Viks

  • 0 in reply to vikash patil
    Expert 1780 points

    Hi Viks.

    I don't know about the situation for OMAP5, but in the case of OMAP4 the omapdrm driver supported only one interface.  So using two X servers was not an option.  This would have been much easier if it did as it would just involve the xorg.conf files each indicating a different display device.

    Regards,
        Steve