Re: [PATCH] qt1010: Fix tuner frequency selection for 546 to 578 MHz range

[Antti Palosaari <crope@iki.fi>]

Moikka Jyrki & all.
If you look qt1010_init() you can see some registers are stored wrongly. 
There is compares that stores register values when .val is given. As you 
can see easily, it should store those when .reg is correct. Store 
register 0x25 when it is register 0x25 not register value. That leads 
calibration wrong => tuner sensitivity is bad.
But if you fix that it will not likely work since ZL10353 demod AGC 
settings are not correct. So you should fix it too.

I hope you will fix that, since it is surely 10th time I am explaining 
that same story for someone :-(

t. Antti




On 12/21/2011 09:42 AM, Jyrki Kuoppala wrote:
> Hi,
>
> To try and shed some more light into the issue, can you describe what
> the problem really is and how would we fix the driver correctly? By
> "work or not", do you mean the fix works with some devices but not with
> some other devices, with some received signal strengths but not some, or
> something else? Do you think there's a risk the fix will break something?
>
> For me, without the fix, some of the major channels from the transmitter
> in the second largest city of Finland are missing, in other words the
> fix would remove a major showstopper. Based on Carlos's note, the
> situation in UK is something similar.
>
> It's of course best to aim for the best possible fix, and if we have
> enough information to do that, that's of course preferable over this
> one. However, if there isn't enough information, and there's no risk of
> the proposed fix breaking something, perhaps this patch should be put in
> as an interim fix and add some notes somewhere that a better fix is
> preferable.
>
> Jyrki
>
>
> 21.12.2011 09:26, Antti Palosaari kirjoitti:
>> Hello,
>> You can try to fix it like that, but it is not proper way. It is kinda
>> of hack which can just work or not. Proper way is to fix that tuner
>> driver correctly and if it was used with zl10353 demoed fix that
>> driver too to support IIRC IF/RF agc settings.
>>
>> regards
>> Antti
>>
>> On 12/20/2011 12:50 PM, Carlos Corbacho wrote:
>>> The patch fixes frequency selection for some UHF frequencies e.g.
>>> channel 32 (562 MHz) on the qt1010 tuner. For those in the UK,
>>> this now means they can tune to the BBC channels (tested on a Compro
>>> Vista T750F).
>>>
>>> One example of problem reports of the bug this fixes can be read at
>>> http://www.freak-search.com/de/thread/330303/linux-dvb_tuning_problem_with_some_frequencies_qt1010,_dvb
>>>
>>>
>>> Based on an original patch by Jyrki Kuoppala<jkp@iki.fi>
>>>
>>> Signed-off-by: Carlos Corbacho<carlos@strangeworlds.co.uk>
>>> Cc: Jyrki Kuoppala<jkp@iki.fi>
>>> Cc: Mauro Carvalho Chehab<mchehab@infradead.org>
>>> ---
>>> drivers/media/common/tuners/qt1010.c | 3 ++-
>>> 1 files changed, 2 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/drivers/media/common/tuners/qt1010.c
>>> b/drivers/media/common/tuners/qt1010.c
>>> index 9f5dba2..8c57d8c 100644
>>> --- a/drivers/media/common/tuners/qt1010.c
>>> +++ b/drivers/media/common/tuners/qt1010.c
>>> @@ -200,7 +200,8 @@ static int qt1010_set_params(struct dvb_frontend
>>> *fe,
>>> if (freq< 450000000) rd[15].val = 0xd0; /* 450 MHz */
>>> else if (freq< 482000000) rd[15].val = 0xd1; /* 482 MHz */
>>> else if (freq< 514000000) rd[15].val = 0xd4; /* 514 MHz */
>>> - else if (freq< 546000000) rd[15].val = 0xd7; /* 546 MHz */
>>> + else if (freq< 546000000) rd[15].val = 0xd6; /* 546 MHz */
>>> + else if (freq< 578000000) rd[15].val = 0xd8; /* 578 MHz */
>>> else if (freq< 610000000) rd[15].val = 0xda; /* 610 MHz */
>>> else rd[15].val = 0xd0;
>>>
>>>
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>>
>>
>


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