From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kapsi.fi ([217.30.184.167]:59890 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750878Ab1K1QCf (ORCPT ); Mon, 28 Nov 2011 11:02:35 -0500 Message-ID: <4ED3B099.8050706@iki.fi> Date: Mon, 28 Nov 2011 18:02:33 +0200 From: Antti Palosaari MIME-Version: 1.0 To: Jens Erdmann CC: linux-media@vger.kernel.org Subject: Re: [PATCH] em28xx: Add Terratec Cinergy HTC Stick References: <11607963.5467764.1322494881126.JavaMail.fmail@mwmweb051> In-Reply-To: <11607963.5467764.1322494881126.JavaMail.fmail@mwmweb051> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hello On 11/28/2011 05:41 PM, Jens Erdmann wrote: > just a few quetstions: > 1. Why is the device named EM2884_BOARD_CINERGY_HTC_STICK and not > EM2884_BOARD_TERRATEC_HTC_STICK like all the other devices from that > vendor? Looks inconsistent to me. Developer have just chosen some value. Maybe he have not looked so carefully about naming. Feel free to fix :) I think correct name is something chip version + "board" + vendor name + device name and model. If name goes something like very long it could be shortened. > 2. I stumbled over http://linux.terratec.de/tv_en.html where they list a NXP TDA18271 > as used tuner for H5 and HTC Stick devices. I dont have any experience in this > kind of stuff but i am just asking. DVB device contain logically three chips. Those are; 1. interface chip (USB, PCI) 2. demodulator 3. tuner Those parts can be integrated even as one silicon (called 3-in-1). Very commonly it seen combination 1.+2. in one chip and 3. in other == total 2 chips. EM2884 is interface chip. It is called usually DVB USB bridge since it transfers bits from demod to computer. TDA18271 is tuner. On the other side of chip is antenna connected as signal input and output is IF (intermediate frequency). Tuner can be thought as chip that transfers signal from RF (radio frequency) to IF (intermediate frequency). Demodulator then takes that IF from tuner and encodes bits out from signal. Interface between demodulator and bridge is bit interface and it is called MPEG2 TS (transport stream) interface. There is also second interface for controlling each chip. That interface is usually I2C bus. Each chip (demod and tuner) is connected to the I2C-bus-adapter which is part of bridge. All command to chips are send using that I2C interface. regards Antti -- http://palosaari.fi/