From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:58843 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756138Ab1EXNAW (ORCPT ); Tue, 24 May 2011 09:00:22 -0400 Message-ID: <4DDBABDE.5010908@iki.fi> Date: Tue, 24 May 2011 16:00:14 +0300 From: Antti Palosaari MIME-Version: 1.0 To: Devin Heitmueller CC: Steve Kerrison , =?ISO-8859-1?Q?R=E9mi_Den?= =?ISO-8859-1?Q?is-Courmont?= , linux-media@vger.kernel.org, vlc-devel@videolan.org Subject: Re: dvb: one demux per tuner or one demux per demod? References: <719f9c4d1bd57d5b2711bc24a9d5c3b1@chewa.net> <1306238734.7397.102.camel@ares> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit List-ID: Sender: On 05/24/2011 03:28 PM, Devin Heitmueller wrote: > 2011/5/24 Steve Kerrison: >> 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 -- http://palosaari.fi/