From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout2.w2.samsung.com ([211.189.100.12]:44803 "EHLO usmailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751616Ab3H1J17 (ORCPT ); Wed, 28 Aug 2013 05:27:59 -0400 Received: from uscpsbgm2.samsung.com (u115.gpu85.samsung.co.kr [203.254.195.115]) by mailout2.w2.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MS800J3KIAL2720@mailout2.w2.samsung.com> for linux-media@vger.kernel.org; Wed, 28 Aug 2013 05:27:57 -0400 (EDT) Date: Wed, 28 Aug 2013 06:27:52 -0300 From: Mauro Carvalho Chehab To: Sylwester Nawrocki Cc: Laurent Pinchart , Guennadi Liakhovetski , Frank =?UTF-8?B?U2Now6RmZXI=?= , Hans Verkuil , Linux Media Mailing List Subject: Re: em28xx + ov2640 and v4l2-clk Message-id: <20130828062752.18604873@samsung.com> In-reply-to: <521DBC3A.7090604@samsung.com> References: <520E76E7.30201@googlemail.com> <6237856.Ni2ROBVUfl@avalon> <20130827110858.01d88513@samsung.com> <5182139.9PqyLJNP0L@avalon> <20130827130041.15db82d5@samsung.com> <521DBC3A.7090604@samsung.com> 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 Wed, 28 Aug 2013 11:00:42 +0200 Sylwester Nawrocki escreveu: > 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(). On an always on clock, there's no sense on defer probe. > > -- > Regards, > Sylwester -- Cheers, Mauro