no DVI output on BB revC3 (using stable-kernel.git)

Hi friends,

I am trying to run ubuntu desktop on my BB revC3. I am using steps
mentioned here to build kernel
http://www.elinux.org/BeagleBoard_Ubuntu_%26_DSP_From_Sources#Build_.26_Prepare_the_Kernel

I am not able to see output on my HDMI display. I am using LG LED TV
it support DVI over HDMI link. The problem as i see is pixel clock for
720p which internally generated by OMAP is 72Mhz whereas it requires
74.25Mhz.

I have tried lot of patches available to make things work.. but I am
not able to see anything on display. as per this thread.. (http://
groups.google.com/group/beagleboard/browse_thread/thread/
89654a5ac60b82a9) it is possible to generate proper clock required for
720p, but patches available does not apply to current kernel tree.

moreover I am not able to see any other display mode working like
1024x768@60 etc.. Please help me out..

Regards,
Ajay Bhargav

Hi friends,

I am trying to run ubuntu desktop on my BB revC3. I am using steps
mentioned here to build kernel
http://www.elinux.org/BeagleBoard_Ubuntu_%26_DSP_From_Sources#Build_.26_Prepare_the_Kernel

I am not able to see output on my HDMI display. I am using LG LED TV
it support DVI over HDMI link. The problem as i see is pixel clock for
720p which internally generated by OMAP is 72Mhz whereas it requires
74.25Mhz.

I'm pretty sure this was a limitation of the core used on the C3, but
i don't remember the full details:
(there is note here about it:
http://elinux.org/BeagleBoardFAQ#linux-omap_display_driver )

I have tried lot of patches available to make things work.. but I am
not able to see anything on display. as per this thread.. (http://
groups.google.com/group/beagleboard/browse_thread/thread/
89654a5ac60b82a9) it is possible to generate proper clock required for
720p, but patches available does not apply to current kernel tree.

moreover I am not able to see any other display mode working like
1024x768@60 etc.. Please help me out..

What happens when you try, (with and without the MR options)

omapfb.mode=1280x720MR-16@60

or even

omapfb.mode=hd720

?

Regards,

I'm pretty sure this was a limitation of the core used on the C3, but
i don't remember the full details:
(there is note here about it:http://elinux.org/BeagleBoardFAQ#linux-omap_display_driver)

I have read about limitations of C3. I felt really annoyed after i
found out :confused: but cant do anything now..
but atleast for modes which are under 72Mhz like 576p@50 they should
be supported. 576p@50 needs clock at 27Mhz.

I tried setting this mode via commandline (I am using angstrom FS) I
still get error as invalid argument..

root@beagleboard:~# fbset -g 720 576 720 576 24 -t 37037 68 12 39 5 64
5
[ 412.803771] detected fb_set_par error, error code: -22
ioctl FBIOPUT_VSCREENINFO: Invalid argument

I have no idea what to do.. or how to test.

What happens when you try, (with and without the MR options)

omapfb.mode=1280x720MR-16@60

or even

omapfb.mode=hd720

?

Regards,

--
Robert Nelsonhttp://www.rcn-ee.com/

I do not see anything on display which is obvious coz I pix clock is
only 72Mhz which is required to be 74.25Mhz.

I have question regarding your kernel. It take a lot of time to build
it :slight_smile: is there any short way to build it? One more interesting thing
about your kernel is.. it create /dev/fb0, fb1 and fb2 devices whereas
if i use mainline kernel directly...(i tried with 3.1.0) i get error
saying no such file... i check on filesystem and there are no fb
devices..

I am feeling so hopeless with beagleboard now. I had a plan to make a
smarthome kind of thing.. so that BB can act as master for all of
multimedia devices + i can use it for browsing internet and do other
simple stuff whenever i want. now that display is not working.. I am
stuck :slight_smile:

Please let me know if you have any pointers... I am kind of lost right
now.. :confused:

Regards,
Ajay Bhargav

Well a good news :slight_smile: i got 576p@50 working on my BB C3. I am using
mainline kernel. I added 576p@50 modeline to modedb.c (a dirty hack).
and passed it as default display argument.. and voila display is up :smiley:

I am bit hopeful now... gonna try ubuntu after this... :slight_smile:

Regards,
Ajay Bhargav

I'm pretty sure this was a limitation of the core used on the C3, but
i don't remember the full details:
(there is note here about it:http://elinux.org/BeagleBoardFAQ#linux-omap_display_driver)

I have read about limitations of C3. I felt really annoyed after i
found out :confused: but cant do anything now..
but atleast for modes which are under 72Mhz like 576p@50 they should
be supported. 576p@50 needs clock at 27Mhz.

I tried setting this mode via commandline (I am using angstrom FS) I
still get error as invalid argument..

root@beagleboard:~# fbset -g 720 576 720 576 24 -t 37037 68 12 39 5 64
5
[ 412.803771] detected fb_set_par error, error code: -22
ioctl FBIOPUT_VSCREENINFO: Invalid argument

I have no idea what to do.. or how to test.

What happens when you try, (with and without the MR options)

omapfb.mode=1280x720MR-16@60

or even

omapfb.mode=hd720

I do not see anything on display which is obvious coz I pix clock is
only 72Mhz which is required to be 74.25Mhz.

That's the whole point of "R" in "omapfb.mode=1280x720MR-16@60"
reduced blanking, it seems to work here on a lot of lcd monitors, when
the beagle can't reach the pixel clock..

I have question regarding your kernel. It take a lot of time to build
it :slight_smile: is there any short way to build it?

It's pretty quick here, on my dual core laptop (10mins).. If you
disable about 7/8 of the 'optional' modules it'll speed up.. It's just
setup to be very generic, and enable almost every module people email
me asking for..

One more interesting thing
about your kernel is.. it create /dev/fb0, fb1 and fb2 devices whereas
if i use mainline kernel directly...(i tried with 3.1.0) i get error
saying no such file... i check on filesystem and there are no fb
devices..

Probably missing something in your config..

I am feeling so hopeless with beagleboard now. I had a plan to make a
smarthome kind of thing.. so that BB can act as master for all of
multimedia devices + i can use it for browsing internet and do other
simple stuff whenever i want. now that display is not working.. I am
stuck :slight_smile:

I'd really retry the hd720 mode, btw, what brand/model is your lcd display?

Regards,

I already tried with 1280x720MR-16@60 video mode. I do not see
anything on display.. after that I tried hd720 even then no display.

I am using LG LED TV model: 42LW6500 probably my TV doesnot support
reduced blanking.. :stuck_out_tongue:

Robert, can you guide me on how to get ubuntu running on BB?

I have been trying ubuntu preinstalled image on BB but I am unable to
get it running.

I now download ubuntu minimal from your website. I want to run my own
kernel.. so i need to change initrd.img too?
how to make initrd for my kernel? how to add it to ubuntu rootfs?

Thanks for help..

Regards,
Ajay Bhargav

It's not required, you can regenerate a new one, by first booting into
the os, then running a script under /boot/uboot/tools
"update_boot_files.sh"...

Regards,

> Hi Robert..
> There is another good news :slight_smile: BB pix clock can easily go beyond 72Mhz.
> The thing is.. pll clock divisor can only divide in multiple of 27
> (which i donno why) so even 1024x768@60 isnt working properly. req pix
> clock is 65 and generated clock is 66.4
>
> as 108Mhz is multiple of 27 so I am able to get 1280x1024@60 (Vesa
> mode) on display without any problem pix clock for the same is
> 108Mhz :slight_smile: Maybe you can find some more information on how to adjust
> the fck divisor to get proper clocks :slight_smile:
>
> Thank you for your last suggestions.. I am now at latest stable kernel
> release.. I also updated initrd successfully from OS. I have also
> updated my modedb.c file for 1280x768@60 display resolution.
>
> I have one more question... I am using minimal-ubuntu release from
> your website. Its working great. I can login successfully. when i
> plugin a device to BB's USB I do not see driver getting loaded
> automatically though ubuntu on my laptop loads immediately. do i need
> to do something special to get driver loading automatically?
>
What kind of device? Most of the automatic driver loading is actually
taken care of the ubuntu userspace. (udev/etc) (of course, there's
always a chance of userspace expecting a specific kernel config, or
even we are missing a config setting for that device..)

> I have purchased new logitech wireless keyboard and mouse combo. on
> laptop it works fine but I have no idea what module is required for
> that keyboard, If you have any information on this please let me know.

This should just be a usb HID device, specially if it comes with a usb/dongle..

Regards,

--
Robert Nelson
http://www.rcn-ee.com/

.. Added missing messages on board ...

Robert,

I think there is some bug in USB.. when I connect a device to USB port
of BB rev C3. it only tries to enumerate it once after that if i
remove and reinsert device it does not get detected. Have you seen
such kind of behavior?

Regards,
Ajay Bhargav