On 05/24/2011 03:28 PM, Devin Heitmueller wrote:
2011/5/24 Steve Kerrison<steve@xxxxxxxxxxxxxxxxx>:
Hi Rémi,
The cxd2820r supports DVB-T/T2 and also DVB-C. As such antti coded up a
multiple front end (MFE) implementation for em28xx then attaches the
cxd2820r in both modes.
I believe you can only use one frontend at once per adapter (this is
certainly enforced in the cxd2820r module), so I don't see how it would
cause a problem for mappings. I think a dual tuner device would register
itself as two adapters, wouldn't it?
But I'm new at this, so forgive me if I've overlooked something or
misunderstood the issue you've raised.
Oh wow, is that what Antti did? I didn't really give much thought but
I can appreciate why he did it (the DVB 3.x API won't allow a single
frontend to advertise support for DVB-C and DVB-T).
Yes I did, since I didn't know there is better way. Is there any other
driver which implements it differently? I think all current MFE drivers
does it like I did. For example look NetUP cx23885 + stv0367.
/dev/dvb/adapter0/
crw-rw----+ 1 root video 212, 2 May 24 15:51 demux0
crw-rw----+ 1 root video 212, 3 May 24 15:51 dvr0
crw-rw----+ 1 root video 212, 0 May 24 15:51 frontend0
crw-rw----+ 1 root video 212, 1 May 24 15:51 frontend1
crw-rw----+ 1 root video 212, 4 May 24 15:51 net0
This is one of the big things that S2API fixes (through S2API you can
specify the modulation that you want). Do we really want to be
advertising two frontends that point to the same demod, when they
cannot be used in parallel? This seems doomed to create problems with
applications not knowing that they are in fact the same frontend.
I was in understanding it is MFE when there is multiple frontends in
same adapter. In that case only one adapter can be used at time. I added
lock to cxd2820r driver, which probably is in wrong place (I think it
should be interface-driver or core which locks).
I'm tempted to say that this patch should be scapped and we should
simply say that you cannot use DVB-C on this device unless you are
using S2API. That would certainly be cleaner but it comes at the cost
of DVB-C not working with tools that haven't been converted over to
S2API yet.
reagrds,
Antti
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