Re: [PATCH 0/1] xc3028: force reload of DTV7 firmware in VHF band with Zarlink demodulator

[Mauro Carvalho Chehab <mchehab@redhat.com>]

On 07-12-2011 11:47, Gianluca Gennari wrote:
> Il 07/12/2011 14:12, Mauro Carvalho Chehab ha scritto:
>> On 06-12-2011 12:33, Gianluca Gennari wrote:
>>> Hi All,
>>>
>>> I have a Terratec Cinergy Hybrid T USB XS stick (USB 0ccd:0042).
>>> This device is made of the following components:
>>> - Empiatech em2880 USB bridge;
>>> - Zarlink zl10353 demodulator;
>>> - Xceive XC3028 tuner;
>>>
>>> For this device, the ZARLINK456 define is set to true so it is using the
>>> firmwares with type D2633 for the XC3028 tuner.
>>>
>>> I found out that:
>>> 1) the DTV7 firmware works fine in VHF band (bw=7MHz);
>>> 2) the DTV8 firmware works fine in UHF band (bw=8MHz);
>>> 3) the DTV78 firmware works fine in UHF band (bw=8MHz) but it doesn not
>>> work at all in VHF band (bw=7MHz);
>>>
>>> In fact, when the DTV78 firmware is loaded and I try to tune a VHF
>>> channel, the frequency lock is ciclically acquired for a second and
>>> immediately lost.
>>> So the proposed patch forces a reload of the DTV7 firmware every time a
>>> 7MHz channel is requested.
>>> The only drawback is that channel change from VHF to UHF or viceversa is
>>> slightly slower.
>>> Devices using the D2620 firmwares are unaffected.
>>
>> Hi Gianluca,
>>
>> The issues with firmware DTV78 x DTV7/DTV8 are old. No matter what we do,
>> we end by having troubles, as the issue is Country-dependent. For example,
>> Australia requires a different firmware than Germany, due to the
>> differences
>> on the VHF/UHF bands.
>>
>> I prefer if you could work into a patch that would add some modprobe
>> parameter
>> to disable the current "autodetection" way, allowing to override the
>> firmware
>> used for VHF and UHF.
>>
>> Thanks,
>> Mauro
>>
>
> Hi Mauro,
> thanks for the feedback. Unfortunately I do not have any info on which
> kind of firmware is needed on other parts of the world. All I know is
> what is happening here in Italy, and what I can understand reading the
> code. I suppose my findings can be extended to the rest of Europe, and
> maybe Africa and Middle-East.

Even in Europe, there are some differences.

> Can you provide a reference about problems in other continents like
> Australia?

All I know is from the constant reports at the ML from users. We used to
have a developer in Australia, but he moved away, and it seems that he lost
interest on DVB development, as we were unable to contact him ever since.
>
> Do you think a simple module parameters that allows to enable/disable
> the usage of the DTV78 firmware would do the trick?

Perhaps one or two module parameters to allow forcing a certain firmware for
VHF and UHF.

> Eventually, do you agree that the default solution should be to DISABLE
> DTV78 firmware, since this seems to be the more robust solution, and let
> the user enable it through the kernel parameter if it is working in his
> country? Or do you prefer the other way around, so by default  DTV78
> firmware is enabled, and users with problems can disable it through the
> kernel module parameter?

AFAIK, DTV78 should be used in Spain and in Germany. Changing the current
default doesn't look a good idea, as it will cause regressions, if the new
way is not backward-compatible.

> Best regards,
> Gianluca
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-media" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html