[linux-dvb] HVR-4000 and analogue tv

Anders Semb Hermansen anders at ginandtonic.no
Wed Sep 24 21:31:39 CEST 2008


Den 24. sep.. 2008 kl. 21.09 skrev Darron Broad:

<snip>

>> I did some more investigating.
>>
>> I thought maybe this had something to do with the tuner, since I got
>> snow. So I enabled debugging for the tuner module (debug=1). What I
>> saw was that when I started watching TV in myth, there was a
>> TUNER_SET_STANDBY after frequency and other things was set. This
>> TUNER_SET_STANDBY did not appear when I was just changing channel  
>> (and
>> picture worked).
>>
>> So I searched the driver for TUNER_STANDBY and found one which I
>> tried. Here is what I did:
>>
>> diff -r e5ca4534b543 linux/drivers/media/video/cx88/cx88-video.c
>> --- a/linux/drivers/media/video/cx88/cx88-video.c       Tue Sep 09
>> 08:29:56 2008 -0700
>> +++ b/linux/drivers/media/video/cx88/cx88-video.c       Wed Sep 24
>> 20:35:46 2008 +0200
>> @@ -1152,7 +1152,8 @@
>>        file->private_data = NULL;
>>        kfree(fh);
>>
>> -       cx88_call_i2c_clients (dev->core, TUNER_SET_STANDBY, NULL);
>> +       printk("Don't set standby mode! TUNER_SET_STANDBY NO SIR!");
>> +       //cx88_call_i2c_clients (dev->core, TUNER_SET_STANDBY, NULL);
>>
>>        return 0;
>> }
>>
>>
>> This fixed it!!
>>
>> I don't know what side effects this will have. Or if this is caused  
>> by
>> wrong use of v4l by mythtv, or driver not implementing it correctly.
>> Those who know the codebase can maybe answer that and come up with a
>> better permanent solution.
>
> I admit I found your fix interesting. In fact, you can reproduce
> this using tvtime and cat.
>
> Eg.
>
>> tvtime -d /dev/video0 &
>> cat /dev/video0

It's a big hack yes. It was easier to change and test the driver  
instead of mythtv. Smaller code base and easier to compile and install.

> The problem in mythtv appears to be in OpenV4L2DeviceAsInput(void)
> where is opens the video device twice although I have no confirmed it.

A ticket in mythtv someone else had with open twice:
http://svn.mythtv.org/trac/ticket/5711
It was closed because it was a feature request without a patch.

I don't know if it's related to my problem or not.


Anders




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