Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1045281AbdDWMTd (ORCPT ); Sun, 23 Apr 2017 08:19:33 -0400 Received: from mail.kapsi.fi ([217.30.184.167]:58681 "EHLO mail.kapsi.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1045264AbdDWMTY (ORCPT ); Sun, 23 Apr 2017 08:19:24 -0400 Subject: Re: [PATCH 1/3] [media] si2157: get chip id during probing To: Andreas Kemnade , mchehab@kernel.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org References: <1489616530-4025-1-git-send-email-andreas@kemnade.info> <1489616530-4025-2-git-send-email-andreas@kemnade.info> From: Antti Palosaari Message-ID: <43216679-3794-14ca-b489-00ac97a57777@iki.fi> Date: Sun, 23 Apr 2017 15:19:21 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.0 MIME-Version: 1.0 In-Reply-To: <1489616530-4025-2-git-send-email-andreas@kemnade.info> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 82.128.188.78 X-SA-Exim-Mail-From: crope@iki.fi X-SA-Exim-Scanned: No (on mail.kapsi.fi); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 713 Lines: 19 On 03/16/2017 12:22 AM, Andreas Kemnade wrote: > If the si2157 is behind a e.g. si2168, the si2157 will > at least in some situations not be readable after the si268 > got the command 0101. It still accepts commands but the answer > is just ffffff. So read the chip id before that so the > information is not lost. > > The following line in kernel output is a symptome > of that problem: > si2157 7-0063: unknown chip version Si21255-\xffffffff\xffffffff\xffffffff That is hackish solution :( Somehow I2C reads should be get working rather than making this kind of work-around. Returning 0xff to i2c reads means that signal strength also shows some wrong static value? regards Antti -- http://palosaari.fi/