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

[Antti Palosaari <crope@iki.fi>]

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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