From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout4.w1.samsung.com ([210.118.77.14]:47278 "EHLO mailout4.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754582Ab3H1JAq (ORCPT ); Wed, 28 Aug 2013 05:00:46 -0400 Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout4.w1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MS8007C2H0JWE80@mailout4.w1.samsung.com> for linux-media@vger.kernel.org; Wed, 28 Aug 2013 10:00:44 +0100 (BST) Message-id: <521DBC3A.7090604@samsung.com> Date: Wed, 28 Aug 2013 11:00:42 +0200 From: Sylwester Nawrocki MIME-version: 1.0 To: Mauro Carvalho Chehab Cc: Laurent Pinchart , Guennadi Liakhovetski , =?ISO-8859-1?Q?Frank_Sch=E4fer?= , Hans Verkuil , Linux Media Mailing List Subject: Re: em28xx + ov2640 and v4l2-clk References: <520E76E7.30201@googlemail.com> <6237856.Ni2ROBVUfl@avalon> <20130827110858.01d88513@samsung.com> <5182139.9PqyLJNP0L@avalon> <20130827130041.15db82d5@samsung.com> In-reply-to: <20130827130041.15db82d5@samsung.com> Content-type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 08/27/2013 06:00 PM, Mauro Carvalho Chehab wrote: >>> > > The thing is that you're wanting to use the clock register as a way to >>> > > detect that the device got initialized. >> > >> > I'm not sure to follow you there, I don't think that's how I want to use the >> > clock. Could you please elaborate ? > > As Sylwester pointed, the lack of clock register makes ov2640 to defer > probing, as it assumes that the sensor is not ready. Hmm, actually there are two drivers here - the sensor driver defers its probing() when a clock provided by the bridge driver is missing. Thus let's not misunderstand it that missing clock is used as an indication of the sensor not being ready. It merely means that the clock provider (which in this case is the bridge driver) has not initialized yet. It's pretty standard situation, the sensor doesn't know who provides the clock but it knows it needs the clock and when that's missing it defers its probe(). -- Regards, Sylwester