Re: si2168/dvbsky - blind-scan for DVB-T2 with PLP fails

[Antti Palosaari <crope@iki.fi>]

On 06/06/2015 05:07 PM, Hurda wrote:
> Thanks, this worked.
> The kernel of Ubuntu 15.04 already was compiled with dynamic debug,
> which saved
> me a lot of time.
> The driver is properly setting stream_id to 1 when needed.
>
> I tried again with the vanilla source and "cmd.args[2] = 0;".
> With the vanilla source, it doesn't find any T2-transponders.

You mean with vanilla source, but without that "cmd.args[2] = 0;" hack 
it does not find any transponders?


> With the modified source, the number of found transponders changes every
> time

You mean with source, modified with that "cmd.args[2] = 0;" hack it 
finds transponders, but not always?

If that is difference, then it sounds just like application is 
requesting some PLP, probably 0, and it will not work as your network 
delivers channels using PLP 1.

"cmd.args[2] = 0;" disables PLP filtering - it sets auto mode. Why it 
likely does not find all channels is too short timeout.

Increase timeout value to 3 second, 900 => 3000, in funtion 
si2168_get_tune_settings()


You didn't provide any debugs to see what PLP ID your application is 
requesting. It is the most important thing I would like to know, as I 
suspect it is wrong.

regards
Antti



> I'm scanning.
> I did four runs: twice it found one mux, once it found two and once it
> found
> three, but never all four.
> I even tried with w_scan-options for longer tuner- and demux-timeouts.
>
> Without changing the position of the antenna or the stick, after
> reinstalling
> the dvbsky-driver, it found all four T2-muxes on the first try.
>
>
> On 04.06.2015 21:28, Antti Palosaari wrote:
>>
>>
>> On 06/04/2015 08:36 PM, Hurda wrote:
>>> How can I enable debug-output to get the log-messages like
>>> http://git.linuxtv.org/cgit.cgi/media_tree.git/tree/drivers/media/dvb-frontends/si2168.c#n164
>>>
>>> ?
>>
>> Compile kernel with dynamic debugs. After that you could enable debugs:
>> modprobe si2168; echo -n 'module si2168 =pft' >
>> /sys/kernel/debug/dynamic_debug/control
>>
>> Antti
>>
>>
>>>
>>> Am 28.05.2015 07:26, schrieb Antti Palosaari:
>>>> On 05/28/2015 01:27 AM, Hurda wrote:
>>>>> Hello.
>>>>>
>>>>> I think I came across a bug in either of the drivers si2168 and dvbsky
>>>>> regarding
>>>>> blind-scanning DVB-T2-frequencies.
>>>>>
>>>>> HW: Technotrend CT2-4400v2 (afaik based on or the same as DVBSky T330)
>>>>>      demod: Si2168-B40
>>>>>      tuner: Si2158-A20
>>>>> OS: Ubuntu 15.04 (kernel 3.19)
>>>>>
>>>>> In Austria, the DVB-T2-service "SimpliTV" is currently airing up to
>>>>> four
>>>>> muxes, next to one or two DVB-T-muxes.
>>>>> In my region, the frequencies are 490MHz, 546MHz, 690MHz, 714MHz for
>>>>> DVB-T2,
>>>>> and 498MHz for DVB-T.
>>>>> These numbers might be of interest when reading the logs.
>>>>>
>>>>> The peculiar aspect of these T2-muxes is that they're aired on PLP 1
>>>>> without
>>>>> there being a PLP 0. I think this is also the root of my problem.
>>>>
>>>> dvbv5-scan is working, but w_scan not?
>>>>
>>>> Could you hack si2168.c file and test?
>>>>
>>>> if (c->delivery_system == SYS_DVBT2) {
>>>>     /* select PLP */
>>>>     cmd.args[0] = 0x52;
>>>>     cmd.args[1] = c->stream_id & 0xff;
>>>> //    cmd.args[2] = c->stream_id == NO_STREAM_ID_FILTER ? 0 : 1;
>>>>     cmd.args[2] = 0;
>>>>     cmd.wlen = 3;
>>>>     cmd.rlen = 1;
>>>>     ret = si2168_cmd_execute(client, &cmd);
>>>>     if (ret)
>>>>         goto err;
>>>> }
>>>>
>>>> Antti
>>>>
>>>>>
>>>>>
>>>>> When doing a blind-scan using w_scan 20140727 on Ubuntu 15.04 (kernel
>>>>> 3.19),
>>>>> w_scan does not find any of these four DVB-T2-muxes.
>>>>> It just finds the DVB-T-mux.
>>>>>
>>>>> Logs:
>>>>> media-tree_dmesg_lsusb.txt http://pastebin.com/0ixFPMSA
>>>>> media-tree_w_scan.txt http://pastebin.com/yyG3jSwj
>>>>>
>>>>> The found transponder:
>>>>> initial_v3_media_build_trunk.conf http://pastebin.com/LmFQavpy
>>>>> initial_v5.conf http://pastebin.com/Jx6kymVt
>>>>>
>>>>> I also tried a fresh checkout from git.linuxtv.org as of last weekend
>>>>> and the
>>>>> most recent w_scan version (20141122).
>>>>>
>>>>> As you can see, w_scan tries to tune(?) the DVB-T2-frequencies, but
>>>>> ultimately doesn't find anything on them.
>>>>>
>>>>>
>>>>> Then I tried the DVBSky-linux-driver[1]
>>>>> (media_build-bst-20150322.tar.gz)[2]
>>>>> from their site, which is using a binary called sit2 for this card.
>>>>> Using this driver, w_scan found all four DVB-T2-muxes and the
>>>>> DVB-T-mux.
>>>>> Additionally, it found the DVB-T2-muxes during the DVB-T-scan.
>>>>>
>>>>> Logs:
>>>>> media_build-bst_dmesg_lsusb.txt http://pastebin.com/vJeDMxtu
>>>>> media_build-bst_w_scan.txt http://pastebin.com/yhwAYjen
>>>>>
>>>>> Found transponders:
>>>>> initial_v3_bst.conf http://pastebin.com/ECKQvRWX
>>>>> initial_v5_bst.conf http://pastebin.com/CbhY6Hpz
>>>>>
>>>>> Of course, doing a channel-scan using dvbv5-scan on these transponders
>>>>> worked
>>>>> too:
>>>>>
>>>>> dvbv5_sit2.conf http://pastebin.com/3W52bbhv
>>>>> dvbv5_sit2.log http://pastebin.com/nc66PTkt
>>>>>
>>>>> Afterwards, I tried to do a channel-scan with the same initial
>>>>> tuning-file
>>>>> using the opensource-driver, which also worked:
>>>>>
>>>>> dvbv5_si2168.conf http://pastebin.com/A6FbqUL1
>>>>> dvbv5_si2168.log http://pastebin.com/ewyVPJR2
>>>>>
>>>>> This should verify that tuning PLP 1 without there being PLP 0 is not
>>>>> the issue.
>>>>>
>>>>>
>>>>> Additionally, if you compare the two channel-lists, you find
>>>>> interesting
>>>>> differences:
>>>>>
>>>>> The scan with si2168 has AUTO for "MODULATION" and "INVERSION" for
>>>>> DVB-T2-channels, and for "CODE_RATE_LP" and "INVERSION" for
>>>>> DVB-T-channels.
>>>>>
>>>>> The scan with sit2 has the respective values in the channel-list.
>>>>>
>>>>> The dvbv5-scan-logs also differ, as using sit2 also displays the
>>>>> signal
>>>>> quality
>>>>> during tuning.
>>>>>
>>>>>
>>>>> I know that there were changes regarding DVB-T2-scanning[3], but as
>>>>> the
>>>>> blog-
>>>>> article specifically mentions si2168 and w_scan to be fully
>>>>> dvbv5-compliant
>>>>> and good for using with DVB-T2, I thought you should know about this
>>>>> particular problem.
>>>>>
>>>>>
>>>>> In the attachment I've packed the previously linked logs, for archival
>>>>> reasons.
>>>>>
>>>>>
>>>>> Thank you for your attention.
>>>>>
>>>>> [1] http://www.dvbsky.net/Support_linux.html
>>>>> [2] http://www.dvbsky.net/download/linux/media_build-bst-150322.tar.gz
>>>>> [3] http://blog.palosaari.fi/2014/09/linux-dvb-t2-tuning-problems.html
>>>>>
>>>>> PS: Interesting comments regarding auto-detection for si2168:
>>>>> http://blog.palosaari.fi/2014/09/linux-dvb-t2-tuning-problems.html?showComment=1427233615765#c8591459871945922951
>>>>>
>>>>>
>>>>>
>>>>> http://blog.palosaari.fi/2014/09/linux-dvb-t2-tuning-problems.html?showComment=1427234034259#c6500661729983566638
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>
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