[linux-dvb] More on the cx24123

Garnet MacPhee garnet at signalpeak.net
Mon Mar 20 20:53:45 CET 2006

Yeasah Pell wrote:
>>>I've been messing around more with the KWorld DVB-S 100 (cx24123 
>>>frontend) card I have here trying to get something tuned, and finally 
>>>had some succcess this weekend.
>>I have been trying to get this card to work, so far without success. I had posted a question to the 
>>forum on March 14 regarding the /dev/dvb entries not being set up.
>>I would be especially interested to know what version of the kernel you are running, and whether you 
>>have applied any patches. Also, I would like to know how you have defined the card in .config.
>>I have held off buying and installing a dish and lnb until I am sure the card is working. Is it 
>>necessary to have the cable from the lnb connected in order to set up /dev/dvb? I would think it 
>>would not be.
>>Thanks and good luck with your card.
> I'm running Fedora Core 4 with a 2.6.15 kernel, with a latest set of 
> v4l-dvb modules installed on top.
> The device entries should (assuming you have a functioning udev) be 
> created automatically as soon as the module is loaded -- this is not 
> dependent upon having anything attached to the card, as you suspect. 
> There's a number of reasons why they might not be:
> 1) You haven't actually loaded the cx88-dvb module or prerequisites. Try 
> "modprobe cx88-dvb" if it isn't in the module list.
> 2) The kernel/drivers you have aren't recent enough to have support for 
> the card you have, or simply doesn't have the driver compiled.
> 3) Your system doesn't have a functioning udev, so the device entries 
> won't be automatically created. You can still make them yourself in the 
> fashion of the olde worlde.
> 4) Hardware issues.
> Defintely make sure you're doing the modprobe, and then see if anything 
> dvb or cx related appears in dmesg.
> Note that if you are trying to install modules from the latest v4l-dvb 
> tree on top of your existing kernel (which is what I do), there's some 
> trickery required to get all of the modules installed (mentioned before 
> on this list) -- basically the problem there is that some conditional 
> tests are done in v4l/Make.config to test which kernel version is in 
> use, but the main makefile includes that file before it does anything to 
> set the variables that Make.config is testing.
> In particular, this block in Make.config (KERNELRELEASE, SUBLEVEL and 
> PATCHLEVEL are all unset in this context):
> ifneq ($(KERNELRELEASE),)
>  CONFIG_DVB_CORE := $(shell test $(SUBLEVEL) -ge 10 -a $(PATCHLEVEL) -ge 
> 6 && e\
> cho m)
>  CONFIG_VIDEO_BUF_DVB := $(shell test $(SUBLEVEL) -ge 12 -a 
> $(PATCHLEVEL) -ge 6\
>  && echo m)
>  CONFIG_VIDEO_DEV := $(shell test $(PATCHLEVEL) -ge 6 && echo m)
>  CONFIG_EM28XX    := $(shell test $(PATCHLEVEL) -ge 6 && echo m)
> endif
> and not having those variables sets causes undesirable effects, such as 
> certain modules not being installed. My quick solution to getting a 
> functioning build was to bypass the kernel tests with hardcoded values 
> for my kernel version, by adding a block like this right after the tests 
> (these values are correct for any kernel post-2.6.12):
> CONFIG_EM28XX    := m
> I think somebody may have said recently that this issue was resolved 
> somehow, but I haven't noticed if it has, since I still have the bypass 
> in there.
> Good luck, and don't give up! Though I kind of wish I had been smart 
> like you and not bought the dish/etc. at the same time as the card -- it 
> took a few weekends to figure out all my issues (not all of which were 
> driver-related of course...), and I was starting to wonder if I'd ever 
> get any singnal off of those things :-)

Thank you for your reply. I now have figured out what I need to do.

I had built the kernel as a single unit, with "y" instead of "m" for all the options. But the DVB 
part MUST be in modules, otherwise the /dev/dvb entries never get built.


The lsmod command shows the following:
root at default:~# lsmod
Module                  Size  Used by
cx88_dvb                3884  -
video_buf_dvb           4268  -
dvb_core               65992  -
cx24123                 7788  -
root at default:~#

I hope that sometime soon this would be fixed so that these modules can again be part of the kernel.

Now I need to order a dish and lnb. :-)

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