[linux-dvb] HVR-4000 and analogue tv

Darron Broad darron at kewl.org
Fri Sep 26 01:42:06 CEST 2008

In message <48DA94F7.1090005 at linuxtv.org>, Steven Toth wrote:

Hi guys

>Anders Semb Hermansen wrote:
>> Den 24. sep.. 2008 kl. 19.20 skrev Darron Broad:
>> <snip>
>>> <snip>
>>>> Does this mean that mythtv is doing something weird or maybe just
>>>> using the v4l api in a different way which the driver cannot handle?
>>> This is feasable. I will take a look if I get the time but this
>>> is more than likely to be when I have other reasons to look
>>> at mythtv so don't expect an immediate response :-)
>> 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.
>Anders, thanks for helping debug this. :)
>This will have odd side effects for other boards. It's an interesting 
>fix and it points us to the real issue, but we need to find a better way 
>to clean this up, before we submit for merge.
>The HVR4000 is a very strange board, we need to be careful when adding 
>generic changes into cx88-*.c that are not conditioned based on (board 
>== HVR4000)
>I welcome your patches, if you find anything else that's odd/strange 
>then let's discuss those also. Your help is very much appreciated.

Two issues have been found with what's been highlighted here.

One has been discovered in cx88-video and another in mythtv.

You will be happy to know that both are fixed.

You can find the mythtv fix here:

The cx88-video fix is also available in the same directory:

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