From mboxrd@z Thu Jan 1 00:00:00 1970 From: Antti Palosaari Subject: Re: [PATCH 1/7] tuner-core: properly initialize media controller subdev Date: Tue, 13 Jan 2015 18:35:08 +0200 Message-ID: <54B5493C.5030102@iki.fi> References: <4ff2de5fce002a6f6f87993440f45e0f198c57cb.1420315245.git.mchehab@osg.samsung.com> <3223125.oELRrvBOf4@avalon> <20150111122553.76394653@recife.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150111122553.76394653-+RedX5hVuTR+urZeOPWqwQ@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mauro Carvalho Chehab , Laurent Pinchart Cc: Linux Media Mailing List , Mauro Carvalho Chehab , Hans Verkuil , Prabhakar Lad , Sakari Ailus , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org On 01/11/2015 04:25 PM, Mauro Carvalho Chehab wrote: > Em Sun, 11 Jan 2015 16:02:41 +0200 > Laurent Pinchart escreveu: >> I'm not too familiar with tuners, do they all have a single output only and no >> input ? > > They have an input: the antenna connector. However, I don't see any need > to map it for most tuners, as there's generally just one input, hardwired > into the tuner chip. > > There are some hardware with 2 antenna connectors, but for different > functions (FM and TV). They're selected automatically when the V4L2 > driver switches between FM and TV. > > In any case, the tuner-core doesn't provide any way to select the > antenna input. > > So, if a driver would need to select the input, it would either need > to not use tuner-core or some patch will be required to add such > functionality inside tuner-core. Tuner has antenna as a input and output is intermediate frequency or baseband (IF/BB (zero-IF)). I think most modern silicon tuners actually has more than one physical antenna inputs - but those are left unused or same physical antenna connector is wired to all those inputs. Sooner or later there will be receiver having multiple antenna connectors which are selectable by software. So let it be at least option easy to add later. regards Antti -- http://palosaari.fi/ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:54596 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752291AbbAMQfP (ORCPT ); Tue, 13 Jan 2015 11:35:15 -0500 Message-ID: <54B5493C.5030102@iki.fi> Date: Tue, 13 Jan 2015 18:35:08 +0200 From: Antti Palosaari MIME-Version: 1.0 To: Mauro Carvalho Chehab , Laurent Pinchart CC: Linux Media Mailing List , Mauro Carvalho Chehab , Hans Verkuil , Prabhakar Lad , Sakari Ailus , linux-api@vger.kernel.org Subject: Re: [PATCH 1/7] tuner-core: properly initialize media controller subdev References: <4ff2de5fce002a6f6f87993440f45e0f198c57cb.1420315245.git.mchehab@osg.samsung.com> <3223125.oELRrvBOf4@avalon> <20150111122553.76394653@recife.lan> In-Reply-To: <20150111122553.76394653@recife.lan> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 01/11/2015 04:25 PM, Mauro Carvalho Chehab wrote: > Em Sun, 11 Jan 2015 16:02:41 +0200 > Laurent Pinchart escreveu: >> I'm not too familiar with tuners, do they all have a single output only and no >> input ? > > They have an input: the antenna connector. However, I don't see any need > to map it for most tuners, as there's generally just one input, hardwired > into the tuner chip. > > There are some hardware with 2 antenna connectors, but for different > functions (FM and TV). They're selected automatically when the V4L2 > driver switches between FM and TV. > > In any case, the tuner-core doesn't provide any way to select the > antenna input. > > So, if a driver would need to select the input, it would either need > to not use tuner-core or some patch will be required to add such > functionality inside tuner-core. Tuner has antenna as a input and output is intermediate frequency or baseband (IF/BB (zero-IF)). I think most modern silicon tuners actually has more than one physical antenna inputs - but those are left unused or same physical antenna connector is wired to all those inputs. Sooner or later there will be receiver having multiple antenna connectors which are selectable by software. So let it be at least option easy to add later. regards Antti -- http://palosaari.fi/