Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752005AbdGRTwd (ORCPT ); Tue, 18 Jul 2017 15:52:33 -0400 Received: from nblzone-211-213.nblnetworks.fi ([83.145.211.213]:60884 "EHLO hillosipuli.retiisi.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751995AbdGRTw3 (ORCPT ); Tue, 18 Jul 2017 15:52:29 -0400 Date: Tue, 18 Jul 2017 22:52:23 +0300 From: Sakari Ailus To: Hugues FRUCHET Cc: "H. Nikolaus Schaller" , Sylwester Nawrocki , Hans Verkuil , Guennadi Liakhovetski , Rob Herring , Mark Rutland , Maxime Coquelin , Alexandre TORGUE , Mauro Carvalho Chehab , devicetree , LKML , Yannick FERTRE , Benjamin Gaignard , linux-arm-kernel , "linux-media@vger.kernel.org" Subject: Re: [PATCH v2 0/7] [PATCH v2 0/7] Add support of OV9655 camera Message-ID: <20170718195223.zrqfrefxxzqfsojd@valkosipuli.retiisi.org.uk> References: <1499073368-31905-1-git-send-email-hugues.fruchet@st.com> <8157da84-1484-8375-1f2b-9831973915b4@kernel.org> <956f17e6-36dd-6733-0d35-9b801ed4244d@xs4all.nl> <2dd3402e-55b0-231d-878f-5ba95ee8cb36@st.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2dd3402e-55b0-231d-878f-5ba95ee8cb36@st.com> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3156 Lines: 71 On Tue, Jul 18, 2017 at 12:53:12PM +0000, Hugues FRUCHET wrote: > > > On 07/18/2017 02:17 PM, H. Nikolaus Schaller wrote: > > Hi, > > > >> Am 18.07.2017 um 13:59 schrieb Hans Verkuil : > >> > >> On 12/07/17 22:01, Sylwester Nawrocki wrote: > >>> Hi Hugues, > >>> > >>> On 07/03/2017 11:16 AM, Hugues Fruchet wrote: > >>>> This patchset enables OV9655 camera support. > >>>> > >>>> OV9655 support has been tested using STM32F4DIS-CAM extension board > >>>> plugged on connector P1 of STM32F746G-DISCO board. > >>>> Due to lack of OV9650/52 hardware support, the modified related code > >>>> could not have been checked for non-regression. > >>>> > >>>> First patches upgrade current support of OV9650/52 to prepare then > >>>> introduction of OV9655 variant patch. > >>>> Because of OV9655 register set slightly different from OV9650/9652, > >>>> not all of the driver features are supported (controls). Supported > >>>> resolutions are limited to VGA, QVGA, QQVGA. > >>>> Supported format is limited to RGB565. > >>>> Controls are limited to color bar test pattern for test purpose. > >>> > >>> I appreciate your efforts towards making a common driver but IMO it would be > >>> better to create a separate driver for the OV9655 sensor. The original driver > >>> is 1576 lines of code, your patch set adds half of that (816). There are > >>> significant differences in the feature set of both sensors, there are > >>> differences in the register layout. I would go for a separate driver, we > >>> would then have code easier to follow and wouldn't need to worry about possible > >>> regressions. I'm afraid I have lost the camera module and won't be able > >>> to test the patch set against regressions. > >>> > >>> IMHO from maintenance POV it's better to make a separate driver. In the end > >>> of the day we wouldn't be adding much more code than it is being done now. > >> > >> I agree. We do not have great experiences in the past with trying to support > >> multiple variants in a single driver (unless the diffs are truly small). > > > > Well, > > IMHO the diffs in ov965x are smaller (but untestable because nobody seems > > to have an ov9650/52 board) than within the bq27xxx chips, but I can dig out > > an old pdata based separate ov9655 driver and extend that to become DT compatible. > > > > I had abandoned that separate approach in favour of extending the ov965x driver. > > > > Have to discuss with Hugues how to proceed. > > > > BR and thanks, > > Nikolaus > > > > As Sylwester and Hans, I'm also in flavour of a separate driver, the > fact that register set seems similar but in fact is not and that we > cannot test for non-regression of 9650/52 are killer for me to continue > on a single driver. > We can now restart from a new fresh state of the art sensor driver > getting rid of legacy (pdata, old gpio, etc...). Agreed. I bet the result will look cleaner indeed although this wasn't one of the complex drivers. It'd be nice that someone was able to test the ov9650/2, too, drivers that are never used tend to break... -- Sakari Ailus e-mail: sakari.ailus@iki.fi XMPP: sailus@retiisi.org.uk