From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout3.w2.samsung.com ([211.189.100.13]:53896 "EHLO usmailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751318AbaANPav (ORCPT ); Tue, 14 Jan 2014 10:30:51 -0500 Received: from uscpsbgm2.samsung.com (u115.gpu85.samsung.co.kr [203.254.195.115]) by usmailout3.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MZE002A6DRD5TA0@usmailout3.samsung.com> for linux-media@vger.kernel.org; Tue, 14 Jan 2014 10:30:49 -0500 (EST) Date: Tue, 14 Jan 2014 13:30:44 -0200 From: Mauro Carvalho Chehab To: Georgi Chorbadzhiyski Cc: linux-media@vger.kernel.org Subject: Re: FE_READ_SNR and FE_READ_SIGNAL_STRENGTH docs Message-id: <20140114133044.1d5276f4@samsung.com> In-reply-to: <52D554BA.3070906@unixsol.org> References: <52D554BA.3070906@unixsol.org> MIME-version: 1.0 Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Em Tue, 14 Jan 2014 17:16:10 +0200 Georgi Chorbadzhiyski escreveu: > Hi guys, I'm confused the documentation on: > > http://linuxtv.org/downloads/v4l-dvb-apis/frontend_fcalls.html#FE_READ_SNR > http://linuxtv.org/downloads/v4l-dvb-apis/frontend_fcalls.html#FE_READ_SIGNAL_STRENGTH > > states that these ioctls return int16_t values but frontend.h states: > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/dvb/frontend.h > > #define FE_READ_SIGNAL_STRENGTH _IOR('o', 71, __u16) > #define FE_READ_SNR _IOR('o', 72, __u16) > > So which one is true? Documentation is wrong. The returned values are unsigned. Would you mind send us a patch fixing it? Btw, the better is to use the new statistics API, when it is available: http://linuxtv.org/downloads/v4l-dvb-apis/FE_GET_SET_PROPERTY.html#frontend-stat-properties As it properly specifies the scale of each value. If you're working in userspace, the libdvbv5 has functions that use the new API automatically when the DVBv5 statistics are available on a DVB driver, via dvb_fe_retrieve_stats(): http://git.linuxtv.org/v4l-utils.git/blob/HEAD:/lib/include/dvb-fe.h -- Cheers, Mauro