From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout2.samsung.com ([203.254.224.25]:15883 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751058Ab1CUGIs (ORCPT ); Mon, 21 Mar 2011 02:08:48 -0400 MIME-version: 1.0 Content-type: text/plain; charset=UTF-8 Received: from epmmp1 (mailout2.samsung.com [203.254.224.25]) by mailout2.samsung.com (Oracle Communications Messaging Exchange Server 7u4-19.01 64bit (built Sep 7 2010)) with ESMTP id <0LIE00F5X9290R60@mailout2.samsung.com> for linux-media@vger.kernel.org; Mon, 21 Mar 2011 15:08:33 +0900 (KST) Received: from TNRNDGASPAPP1.tn.corp.samsungelectronics.net ([165.213.149.150]) by mmp1.samsung.com (iPlanet Messaging Server 5.2 Patch 2 (built Jul 14 2004)) with ESMTPA id <0LIE00FUK9295K@mmp1.samsung.com> for linux-media@vger.kernel.org; Mon, 21 Mar 2011 15:08:33 +0900 (KST) Date: Mon, 21 Mar 2011 15:08:33 +0900 From: "Kim, HeungJun" Subject: Re: [PATCH] Add support for M-5MOLS 8 Mega Pixel camera In-reply-to: <4D8503EC.6040103@gmail.com> To: Sylwester Nawrocki Cc: Kim HeungJun , Sylwester Nawrocki , Hans Verkuil , Laurent Pinchart , Kyungmin Park , linux-media Reply-to: riverful.kim@samsung.com Message-id: <4D86EB61.1010706@samsung.com> Content-transfer-encoding: 8BIT References: <1300282723-31536-1-git-send-email-riverful.kim@samsung.com> <4D84B183.7020709@gmail.com> <3985908C-2E67-4274-AA8F-E5F70745DED7@gmail.com> <4D8503EC.6040103@gmail.com> List-ID: Sender: Hi Sylwester, 2011-03-20 오전 4:28, Sylwester Nawrocki 쓴 글: > On 03/19/2011 04:11 PM, Kim HeungJun wrote: >> Hi Sylwester, >> >> Thanks for the reviews. :) >> >> 2011. 3. 19., 오후 10:37, Sylwester Nawrocki 작성: >> >>> Hi HeungJun, >>> >>> On 03/16/2011 02:38 PM, Kim, Heungjun wrote: >>>> Add I2C/V4L2 subdev driver for M-5MOLS camera sensor with integrated >>>> image signal processor. >>>> [snip] >>>> >>>> 3. Speed-up whole I2C operation >>>> : I've tested several times for decreasing the stabilization time >>>> while I2C communication, and I have find proper time. Of course, >>>> it's more faster than previous version. >>> >>> That sounds good. Do you think the delays before I2C read/write could >>> be avoided in some (if not all) cases by using some status registers >>> polling? >> I don't understand literally. Could you explain more detailed with some examples? >> My understanding is that it might be an issues or problem when getting some >> status registers with polling it. is it right? > > My concern is that we might not need an extra delay between consecutive > read or write operations in every case. Possibly it would be enough > to read the status of some operations instead. But that just what I suspect. Ah, I understand. The consecutive delay needs to read/write operations. Because, in non-delay cases, I found the values is not changed to be read when the driver is reading continuously at the different address. I means, if there is not regular amount of delay in r/w operations, the value is kept the previous value to be read by I2C operation. It's the same way in writing case. It's wierd. It might be different the kind of M-5MOLS sensor's FW and packaging type. But, I expect that the internal ARM core of M-5MOLS takes time to proceed something and to load values through I2C bus for the host process. Regards, Heungjun Kim