On 07-12-2011 13:51, Gianluca Gennari wrote:
Il 07/12/2011 16:45, Gianluca Gennari ha scritto:
Il 07/12/2011 16:05, Mauro Carvalho Chehab ha scritto:
On 07-12-2011 12:53, Gianluca Gennari wrote:
Il 07/12/2011 15:20, Mauro Carvalho Chehab ha scritto:
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.
OK, so the validity of my findings are restricted to Italy.
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.
Seems reasonable.
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.
With the proposed patch DTV78 will be used in UHF band, while DTV7 in
VHF band. Will this make any difference in Spain or Germany?
Not sure. I don't live there ;)
What about a kernel parameter to specify the country?
Something like:
country={0-4}
DEFAULT=0,ITALY=1,GERMANY=2,SPAIN=3,AUSTRALIA=4
Then we could specify a well-defined behavior for each country, hiding
the firmware-related problems to the user (which will have problems
understanding parameters like force-DTV7-firmware-in-VHF-band).
All I need to know is what is the best behavior for each country.
That's the hardest part ;) We would need someone on each possible Country,
in order to test. Also, a per-country setup like that sucks. Ideally, the
driver should use the bandwidh and the other information at the standard
DVB
parameters, in order to select the right firmware. This works with all
other
frontends. Not sure what's broken on xc3028 design that it requires a
per-country
hack. I suspect that it is not a pure per-country hack, but it is also per
demod.
As we don't have much complains about it nowadays, I assume that the
current
behavior is ok for most users. So, a parameter would be used only for those
where the default behavior doesn't work.
Btw, we already have a similar parameter to force the audio demodulation
standard,
due to the same reasons.
Regards,
Mauro
Probably there are no complains about the firmware because in most
countries VHF is not used at all, or is only used for marginal TV
stations.
Makes sense. Well, it is not hard to detect VHF. If the DTV bandwidth is
properly filled, detecting between 8/7/6 MHz is also easy.
In Italy instead the main DTT mux (RAI mux 1) is broadcasted
in VHF band for historical reasons, so many Italian users are concerned
about it. I've already faced problems related to DTT VHF reception, that
were never noticed before by users from other countries.
Moreover, another problem is that there are 2 firmwares types: D2633 and
D2620;
AFAIKT, this is related to the demux sensibility: D2633 is normal level,
D2620 is lower output level.
also there are 2 completely different files: xc3028-v27.fw and
xc3028L-v36.fw.
The v3.6 is for xc3028L (low power). It was reported that using v2.7 on a
xc3028L will cause it to overheat.
In my case, my stick uses firmwares of type D2633 from file
xc3028-v27.fw; I cannot test anything else. It is also possible that the
VHF part of the DTV78 firmware of type D2633 in file xc3028-v27.fw is
simply broken.
Maybe. From my remarks, Australia would use only 7MHz firmware on both VHF
and UHF bandwidths. B/G countries would use 7/8 MHz. There were several
discussions at the ML by the time we've added support for this tuner, and
later on. The logs for it can provide some useful info about the changes.
As far as I know, this firmware is older than than the
first DTT mux in VHF band here in Italy, so maybe it was optimized for
analog reception and has never been tested with digital modulations.
What about a module parameter "alternative-VHF-firmware" which can be
either on/off (default=off)?
By default, we keep current behavior; when enabled, DTV7 firmware is
always loaded for VHF channels, for all firmware types and files.
Maybe vhf_firmware, being 0 (default behavior), 6, 7, 8 or 78?
Best regards,
Gianluca
Thinking about it, maybe a shorter name like "vhf-fw" =
default(0)/alternative(1) would be better.
Best,
Gianluca
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
