[mythtv-users] Nebula DVB-T problem after kernel update

Otto Kolsi otto at kolsi.net
Sat Feb 18 15:25:01 UTC 2006


>> I had working Fedora Core 4 Myth installation with Nebula DVB-T card, 
>> with kernel 2.6.14. I pretty much followed 
>> <http://www.dtvforum.info/lofiversion/index.php/t13523.html> and got 
>> Nebula card working nicely.
>>
>> Then I (stupid me) upgraded kernel to 2.6.15 with yum and booted the 
>> machine couple times with the new kernel. After that Nebula doesn't work 
>> anymore, with either kernel. DVB devices are there, kernel modules seem 
>> to be right, card is recognized at boot, no errors in dmesg etc. But 
>> e.g. 'scan' or 'dvbstream' won't work anymore.
>>
>> Can anyone give me a hint where to look? Does booting with new kernel 
>> change devices, permissions, kernel modules or something else? Now that 
>> I'm back using the previous kernel, should everything be like before the 
>> upgrade (well, it isn't but anyway..)?
>   
> I have the same kernel and card and did exactly what you did.
> 
> I did have to manually add /dev/dvb/adaptor and also add in a new 
> module. I did this with /etc/rc.local (I'm just getting it going so 
> please don;t anybody bitch about it)
> 
> modprobe dvb-bt8xx
> mkdir -p /dev/dvb/adapter0
> mknod /dev/dvb/adapter0/audio0 c 250 1
> mknod /dev/dvb/adapter0/ca0 c 250 6
> mknod /dev/dvb/adapter0/demux0 c 250 4
> mknod /dev/dvb/adapter0/dvr0 c 250 5
> mknod /dev/dvb/adapter0/frontend0 c 250 3
> mknod /dev/dvb/adapter0/net0 c 250 7
> mknod /dev/dvb/adapter0/osd0 c 250 8
> mknod /dev/dvb/adapter0/video0 c 250 0
> chmod ugo+rw /dev/dvb/adapter0/*
> 
> Let me know if this doesn't work.

I have followed the HOWTO (link above) and added the 51-dvb.rules -file 
to /etc/udev/rules.d/. After boot I get only demux0, dvr0, frontend0 and 
net0 devices, I wonder if there's something wrong with udev.. I think it 
worked earlier with only these devices.

Just to be sure, I added the rest (audio0, ca0, osd0, video0) through a 
init-script but that didn't help.

Running tzap gives following:
--------------------------------------------
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
tuning to 562000000 Hz
video pid 0x0200, audio pid 0x028a
status 00 | signal 697f | snr 0000 | ber 00000000 | unc 00000000 |
status 05 | signal 00af | snr 0000 | ber 00000000 | unc 00000000 |
status 05 | signal 000f | snr 0000 | ber 00000000 | unc 00000000 |
status 05 | signal 007f | snr 0000 | ber 00000000 | unc 00000000 |
status 01 | signal 006f | snr 0000 | ber 00000000 | unc 00000000 |
status 05 | signal 00cf | snr 0000 | ber 00000000 | unc 00000000 |
status 05 | signal 008f | snr 0000 | ber 00000000 | unc 00000000 |
--------------------------------------------

It looks like the signal is not good enough, there is no FE_LOCK.. but 
this worked well before the kernel upgrade. I can verify with a 
set-top-box that DVB-T signal is okay.

If you compare following 'lsmod' output with yours, do you see anything 
strange:
--------------------------------------------
Module                  Size  Used by
dvb_bt8xx              15173  0
nxt6000                 7621  1 dvb_bt8xx
mt352                   6597  1 dvb_bt8xx
dvb_pll                10949  1 dvb_bt8xx
sp887x                  7365  1 dvb_bt8xx
dst_ca                 13505  1 dvb_bt8xx
dst                    22981  2 dvb_bt8xx,dst_ca
bt878                  10553  2 dvb_bt8xx,dst
dvb_core               81769  2 dvb_bt8xx,dst_ca
cx24110                 8005  1 dvb_bt8xx
or51211                 9669  1 dvb_bt8xx
lgdt330x                7901  1 dvb_bt8xx
bttv                  168881  2 dvb_bt8xx,bt878
video_buf              21957  1 bttv
i2c_algo_bit            9289  1 bttv
v4l2_common             5953  1 bttv
btcx_risc               5065  1 bttv
tveeprom               15057  1 bttv
videodev                9665  1 bttv
i2c_piix4               9041  0
i2c_core               21697  12 dvb_bt8xx,nxt6000,mt352,sp887x, 
dst,cx24110,or51211,lgdt330x,bttv,i2c_algo_bit,tveeprom,i2c_piix4
--------------------------------------------

I've tried to remove DVB related modules and then modprobe them back. 
But that hasn't helped. I wonder whether I should try to remove the 
latest kernel with yum so that it would 'put everything back to how it 
was before the upgrade' :) Probably that wouldn't help..
-- 
   Otto


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