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Yocto Fido iMX6Q: no screens found, no /dev/fb0

Question asked by Adrian McGrath on Jan 13, 2016

Hello All

 

I'm using the Yocto Fido (1.8) community BSP with kernel 3.14.28 to build a GUI image (based on fsl-image-gui) for an iMX6Q custom board (based on SabreSD).

 

The image has been successfully built and when run gives me full console access. On boot-up I see the Freescale U-Boot splash screen so I know that the HDMI interface can work. However, after loading the Linux kernel I see a "No signal" message on my HDTV and X windows is not started.

 

My U-Boot kernel command line is:

console=ttymxc2,115200 root=/dev/mmcblk2p2 rootwait rw video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24

so I expected to see X windows coming out of the HDMI port onto the HDTV.

 

However, the boot log shows that X windows does not start due to the error underlined in red (see Boot log below).

 

It seems clear that the issue is due to no "/dev/fb0" device file and indeed this file is missing from the "/dev" directory.

 

To me, this appears to be a kernel config issue. However, my defconfig contains the following (please see attached file for full defconfig):

CONFIG_DRM_VIVANTE=y

CONFIG_DRM=y

CONFIG_HDMI=y

CONFIG_FB=y

CONFIG_FB_IMX=y

 

My questions to my learned colleagues in the community are:

1) Could anyone suggest why the /dev/fb0 device not created and what I need to change in order to rectify the issue?

2) Is there any significance to the "unknown username "xuser" comment on the following line?

 

Many thanks in advance.

 

 

 

Boot log:

...

Error opening /dev/fb0: No such file or directory

Starting udev

...

Starting Xserver

^[[59;105R^[[59;105RStarting system message bus: open /dev/fb0: No such file or directory

Unknown username "xuser" in message bus configuration file

dbus.

Starting Connection Manager

Starting Dropbear SSH server: dropbear.

Starting rpcbind daemon...done.

igb: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX/TX

8021q: adding VLAN 0 to HW filter on device eth0

starting statd: done

Starting advanced power management daemon: No APM support in kernel

(failed.)

NFS daemon support not enabled in kernel

Starting syslogd/klogd: done

* Starting Avahi mDNS/DNS-SD Daemon: avahi-daemon

   ...done.

Starting Watchdog: Stopping watchdog keepalive daemon...

0

Starting watchdog daemon...

0

No state file exists, creating

Gpio125 does not exist

Starting OProfileUI server

^[[59;105RStarting autohdmi:

Running local boot scripts (/etc/rc.local).

 

Poky (Yocto Project Reference Distro) 1.8 imx6qswan /dev/ttymxc2

 

imx6qswan login: root

root@imx6qswan:~# more /etc/X11/xorg.conf

Section "Device"

   Identifier  "i.MX Accelerated Framebuffer Device"

   Driver   "vivante"

   Option   "fbdev"   "/dev/fb0"

   Option   "vivante_fbdev" "/dev/fb0"

   Option   "HWcursor"  "false"

EndSection

Section "Screen"

   Identifier   "Default Screen"

   Device   "i.MX Accelerated Framebuffer Device"

EndSection

Section "ServerLayout"

   Identifier   "Default Layout"

   Screen   "Default Screen"

EndSection

root@imx6qswan:~#

 

 

 

/etc/X11/xorg.conf:

Section "Device"

   Identifier  "i.MX Accelerated Framebuffer Device"

   Driver   "vivante"

   Option   "fbdev"   "/dev/fb0"

   Option   "vivante_fbdev" "/dev/fb0"

   Option   "HWcursor"  "false"

EndSection

Section "Screen"

   Identifier   "Default Screen"

   Device   "i.MX Accelerated Framebuffer Device"

EndSection

Section "ServerLayout"

   Identifier   "Default Layout"

   Screen   "Default Screen"

EndSection

 

 

 

/var/log/Xorg.0.log:

...

[977609.560] (II) Loading sub module "fbdevhw"

[977609.560] (II) LoadModule: "fbdevhw"

[977609.560] (II) Loading /usr/lib/xorg/modules/libfbdevhw.so

[977609.564] (II) Module fbdevhw: vendor="X.Org Foundation"

[977609.564]    compiled for 1.16.3, module version = 0.0.2

[977609.564]    ABI class: X.Org Video Driver, version 18.0

[977609.564] (EE) open /dev/fb0: No such file or directory

[977609.564] (EE) No devices detected.

[977609.565] (EE)          

Fatal server error:        

[977609.565] (EE) no screens found(EE)

[977609.565] (EE)          

Please consult the The X.Org Foundation support

         at http://wiki.x.org

for help.                 

[977609.565] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.

[977609.565] (EE)           

Original Attachment has been moved to: defconfig-no-fb.zip

Original Attachment has been moved to: bootlog-no-fb.zip

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