linux-kernel - Re: How to use "DTV_FE_CAPABILITY" command for Frontend.h of Linux DVB

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Message-ID: <20210902110347.14939-1-yp.wu@mediatek.com>
Date:   Thu, 2 Sep 2021 19:03:47 +0800
From:   YP WU <yp.wu@...iatek.com>
To:     <mchehab@...nel.org>
CC:     <Jason-BF.Huang@...iatek.com>, <Lecopzer.Chen@...iatek.com>,
        <francis.lee@...iatek.com>, <gustavoars@...nel.org>,
        <hverkuil-cisco@...all.nl>, <leo.hsiao@...iatek.com>,
        <linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>,
        <yp.wu@...iatek.com>
Subject: Re: How to use "DTV_FE_CAPABILITY" command for Frontend.h of Linux DVB

Hello, Mr.Mauro,
      Frist of all, thanks for your reply and Sorry to reply late.

We know that everything is controlled by /dev/dvb/frontend.

It is assumed that the device node "dvb/frontend0", "dvb/frontend1" and "dvb/frontend2" use the input signal from the same satellite antenna. In addition, "dvb/frontend0", "dvb/frontend1", and "dvb/frontend2" are premised on receiving broadcast signals at the same time under the condition that the same voltage is always supplied to the satellite antenna.

Therefore, Our TV uses an HW circuit equipped with only one LNB IC.

Since only one LNB IC is installed, the design policy of including and controlling the same LNB IC in "dvb/frontend0", "dvb/frontend1" and "dvb/frontend2" is complicated and difficult to understand. It is more simpler and easier to design to separate the LNB IC into "dvb/frontend3" and control the LNB IC from "dvb0.frontend3". Therefore, we want to separate LNB to different device node.

BRs,
YP