[linux-dvb] encrypted channels & headend encoder

[Douglas Kosovic <douglask@dstc.edu.au>]

Hi,

The Linux DVB driver has problems with encrypted channels if a Harmonic
DiviCom MPEG-2 encoder is used at the headend. This might be the same
problem that a number of set top boxes in early 2000 had with DiviCom
DVB streams, before their firmware was upgraded. This also might explain
some, but not all the problems people are have been having with CI CAMS
and the Linux DVB driver, so I though I might as well post something.

GPIO0 irq 5 seems to go missing, i.e. the DATA_COMMON_INTERFACE case
statement of function debiirq() in driver/dvb.c is never (or extremely
rarely) invoked.

Here is a snippet of syslog corresponding to a channel change to an
encrypted channel that has a DiviCom encoder at the head end (I changed
'#if 0' to '#if 1' in DATA_FSECTION case statement of debiirq() for more
debugging):
Nov 13 14:05:03 dvb kernel: mon_tune: locked on 1st try
Nov 13 14:05:03 dvb kernel: GPIO0 irq 2305 62
Nov 13 14:05:03 dvb kernel: GPIO0 irq 01
Nov 13 14:05:03 dvb kernel: 09: 02 b0 3b 03 2a db  003e
Nov 13 14:05:03 dvb kernel: GPIO0 irq 1281 40
Nov 13 14:05:03 dvb kernel: GPIO0 irq 01
Nov 13 14:05:03 dvb kernel: 05: 02 b0 25 03 28 cd  0028
Nov 13 14:05:03 dvb kernel: GPIO0 irq 1537 40
Nov 13 14:05:03 dvb kernel: GPIO0 irq 01
Nov 13 14:05:03 dvb kernel: 06: 02 b0 25 03 28 cd  0028

If I use tuxzap and rapidly keep clicking on a channel, I sometimes see
a GPIO0 irq 5 (which results in a decrypted picture).

Anyway, for completness here is a snippet of syslog for a working
channel change corresponding to a non-DiviCom encoder:
Nov 13 14:04:25 dvb kernel: mon_tune: locked on 1st try
Nov 13 14:04:26 dvb kernel: GPIO0 irq 5 6
Nov 13 14:04:26 dvb kernel: GPIO0 irq 05
Nov 13 14:04:26 dvb kernel: dvb0: 0e 00 41 cc 02 04 A
Nov 13 14:04:26 dvb kernel: GPIO0 irq 5 32
Nov 13 14:04:26 dvb kernel: GPIO0 irq 05
Nov 13 14:04:26 dvb kernel: dvb0: 0c 00 0f 00 2e 00 78 11 00 00 ff ff 2e
08 53 c8 00 00 00 90 00 00 00 00 2e 08 54 58 2e 00 42 23   . x     .
S         . TX. B#

I think the DiviCom problems are all timming related, but I'm not
exactly sure how.

Cheers,
Doug.


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