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Tue, 30 Jun 2020 23:59:15 -0800 Received: from MTKMBS31DR.mediatek.inc (172.27.6.102) by MTKMBS62N1.mediatek.inc (172.29.193.41) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 1 Jul 2020 00:59:08 -0700 Received: from MTKCAS36.mediatek.inc (172.27.4.186) by MTKMBS31DR.mediatek.inc (172.27.6.102) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 1 Jul 2020 15:59:07 +0800 Received: from [10.17.3.153] (10.17.3.153) by MTKCAS36.mediatek.inc (172.27.4.170) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Wed, 1 Jul 2020 15:59:05 +0800 Message-ID: <1593590324.17166.30.camel@mhfsdcap03> Subject: Re: [PATCH V11 2/2] media: i2c: ov02a10: Add OV02A10 image sensor driver From: Dongchun Zhu To: Tomasz Figa Date: Wed, 1 Jul 2020 15:58:44 +0800 In-Reply-To: References: <20200630024942.20891-1-dongchun.zhu@mediatek.com> <20200630024942.20891-3-dongchun.zhu@mediatek.com> <20200630095430.GF16711@paasikivi.fi.intel.com> <20200630143705.GW3703480@smile.fi.intel.com> X-Mailer: Evolution 3.10.4-0ubuntu2 MIME-Version: 1.0 X-TM-SNTS-SMTP: 560D0B0501A9BD5D2873241F011FACDD2523717978D3BD25795468ED446CA7E02000:8 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200701_035917_214398_54BBA774 X-CRM114-Status: GOOD ( 23.19 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Nicolas Boichat , Mauro Carvalho Chehab , srv_heupstream , linux-devicetree , Linus Walleij , Shengnan Wang =?UTF-8?Q?=28=E7=8E=8B=E5=9C=A3=E7=94=B7=29?= , Louis Kuo , Bartosz Golaszewski , Sj Huang , Rob Herring , "moderated list:ARM/Mediatek SoC support" , dongchun.zhu@mediatek.com, Sakari Ailus , Matthias Brugger , Cao Bing Bu , Andy Shevchenko , "list@263.net:IOMMU DRIVERS , Joerg Roedel , " , Linux Media Mailing List Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 2020-06-30 at 16:40 +0200, Tomasz Figa wrote: > On Tue, Jun 30, 2020 at 4:37 PM Andy Shevchenko > wrote: > > > > On Tue, Jun 30, 2020 at 04:21:31PM +0200, Tomasz Figa wrote: > > > On Tue, Jun 30, 2020 at 4:19 PM Tomasz Figa wrote: > > > > On Tue, Jun 30, 2020 at 11:54 AM Sakari Ailus > > > > wrote: > > > > ... > > > > > > > > + ov02a10->rst_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW); > > > > > > > > > > > > > > > Shouldn't this be GPIOD_OUT_HIGH? That's the state it'll be after powering > > > > > the sensor off the first time. Alternatively make reset signal high in > > > > > runtime suspend callback. > > > > > > > > We might want to keep the signals low when the regulators are powered > > > > down, to reduce the leakage. > > > > > > Ah, I actually recall that the reset pin was physically active low, so > > > we would indeed better keep it at HIGH. Sorry for the noise. > > > > Here HIGH means "asserted", so in the code above it's LOW, means "deasserted", > > i.o.w. non-reset state. I dunno what is better, it depends to the firmware / > > driver expectations of the device configuration (from the power point of view, > > HIGH makes sense here, and not LOW, i.o.w. asserted reset line). > > > > And nice of the logical state that it doesn't depend to the active low / high > > (the latter just transparent to the user). > > Yeah, after reading through the GPIO subsystem documentation and > discussing with a bunch of people on how to interpret it, we concluded > that the driver needs to deal only with the logical state of the > signal. > > Actually, I later realized that the problem of leakage should likely > be solved by pinctrl suspend settings, based on given hardware > conditions, rather than the driver explicitly. > Thank you for all your explanation. Fixed in next release. > Best regards, > Tomasz _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel