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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 CC: Andy Shevchenko , Sakari Ailus , Linus Walleij , Bartosz Golaszewski , Mauro Carvalho Chehab , Rob Herring , Mark Rutland , Nicolas Boichat , "Matthias Brugger" , Cao Bing Bu , srv_heupstream , "moderated list:ARM/Mediatek SoC support" , "list@263.net:IOMMU DRIVERS , Joerg Roedel ," , Sj Huang , Linux Media Mailing List , linux-devicetree , Louis Kuo , "Shengnan Wang =?UTF-8?Q?=28=E7=8E=8B=E5=9C=A3=E7=94=B7=29?=" , 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> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 MIME-Version: 1.0 X-TM-SNTS-SMTP: 560D0B0501A9BD5D2873241F011FACDD2523717978D3BD25795468ED446CA7E02000:8 X-MTK: N Content-Transfer-Encoding: base64 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org T24gVHVlLCAyMDIwLTA2LTMwIGF0IDE2OjQwICswMjAwLCBUb21hc3ogRmlnYSB3cm90ZToNCj4g T24gVHVlLCBKdW4gMzAsIDIwMjAgYXQgNDozNyBQTSBBbmR5IFNoZXZjaGVua28NCj4gPGFuZHJp eS5zaGV2Y2hlbmtvQGxpbnV4LmludGVsLmNvbT4gd3JvdGU6DQo+ID4NCj4gPiBPbiBUdWUsIEp1 biAzMCwgMjAyMCBhdCAwNDoyMTozMVBNICswMjAwLCBUb21hc3ogRmlnYSB3cm90ZToNCj4gPiA+ IE9uIFR1ZSwgSnVuIDMwLCAyMDIwIGF0IDQ6MTkgUE0gVG9tYXN6IEZpZ2EgPHRmaWdhQGNocm9t aXVtLm9yZz4gd3JvdGU6DQo+ID4gPiA+IE9uIFR1ZSwgSnVuIDMwLCAyMDIwIGF0IDExOjU0IEFN IFNha2FyaSBBaWx1cw0KPiA+ID4gPiA8c2FrYXJpLmFpbHVzQGxpbnV4LmludGVsLmNvbT4gd3Jv dGU6DQo+ID4NCj4gPiAuLi4NCj4gPg0KPiA+ID4gPiA+ID4gKyAgICAgb3YwMmExMC0+cnN0X2dw aW8gPSBkZXZtX2dwaW9kX2dldChkZXYsICJyZXNldCIsIEdQSU9EX09VVF9MT1cpOw0KPiA+ID4g PiA+DQo+ID4gPiA+ID4NCj4gPiA+ID4gPiBTaG91bGRuJ3QgdGhpcyBiZSBHUElPRF9PVVRfSElH SD8gVGhhdCdzIHRoZSBzdGF0ZSBpdCdsbCBiZSBhZnRlciBwb3dlcmluZw0KPiA+ID4gPiA+IHRo ZSBzZW5zb3Igb2ZmIHRoZSBmaXJzdCB0aW1lLiBBbHRlcm5hdGl2ZWx5IG1ha2UgcmVzZXQgc2ln bmFsIGhpZ2ggaW4NCj4gPiA+ID4gPiBydW50aW1lIHN1c3BlbmQgY2FsbGJhY2suDQo+ID4gPiA+ DQo+ID4gPiA+IFdlIG1pZ2h0IHdhbnQgdG8ga2VlcCB0aGUgc2lnbmFscyBsb3cgd2hlbiB0aGUg cmVndWxhdG9ycyBhcmUgcG93ZXJlZA0KPiA+ID4gPiBkb3duLCB0byByZWR1Y2UgdGhlIGxlYWth Z2UuDQo+ID4gPg0KPiA+ID4gQWgsIEkgYWN0dWFsbHkgcmVjYWxsIHRoYXQgdGhlIHJlc2V0IHBp biB3YXMgcGh5c2ljYWxseSBhY3RpdmUgbG93LCBzbw0KPiA+ID4gd2Ugd291bGQgaW5kZWVkIGJl dHRlciBrZWVwIGl0IGF0IEhJR0guIFNvcnJ5IGZvciB0aGUgbm9pc2UuDQo+ID4NCj4gPiBIZXJl IEhJR0ggbWVhbnMgImFzc2VydGVkIiwgc28gaW4gdGhlIGNvZGUgYWJvdmUgaXQncyBMT1csIG1l YW5zICJkZWFzc2VydGVkIiwNCj4gPiBpLm8udy4gbm9uLXJlc2V0IHN0YXRlLiBJIGR1bm5vIHdo YXQgaXMgYmV0dGVyLCBpdCBkZXBlbmRzIHRvIHRoZSBmaXJtd2FyZSAvDQo+ID4gZHJpdmVyIGV4 cGVjdGF0aW9ucyBvZiB0aGUgZGV2aWNlIGNvbmZpZ3VyYXRpb24gKGZyb20gdGhlIHBvd2VyIHBv aW50IG9mIHZpZXcsDQo+ID4gSElHSCBtYWtlcyBzZW5zZSBoZXJlLCBhbmQgbm90IExPVywgaS5v LncuIGFzc2VydGVkIHJlc2V0IGxpbmUpLg0KPiA+DQo+ID4gQW5kIG5pY2Ugb2YgdGhlIGxvZ2lj YWwgc3RhdGUgdGhhdCBpdCBkb2Vzbid0IGRlcGVuZCB0byB0aGUgYWN0aXZlIGxvdyAvIGhpZ2gN Cj4gPiAodGhlIGxhdHRlciBqdXN0IHRyYW5zcGFyZW50IHRvIHRoZSB1c2VyKS4NCj4gDQo+IFll YWgsIGFmdGVyIHJlYWRpbmcgdGhyb3VnaCB0aGUgR1BJTyBzdWJzeXN0ZW0gZG9jdW1lbnRhdGlv biBhbmQNCj4gZGlzY3Vzc2luZyB3aXRoIGEgYnVuY2ggb2YgcGVvcGxlIG9uIGhvdyB0byBpbnRl cnByZXQgaXQsIHdlIGNvbmNsdWRlZA0KPiB0aGF0IHRoZSBkcml2ZXIgbmVlZHMgdG8gZGVhbCBv bmx5IHdpdGggdGhlIGxvZ2ljYWwgc3RhdGUgb2YgdGhlDQo+IHNpZ25hbC4NCj4gDQo+IEFjdHVh bGx5LCBJIGxhdGVyIHJlYWxpemVkIHRoYXQgdGhlIHByb2JsZW0gb2YgbGVha2FnZSBzaG91bGQg bGlrZWx5DQo+IGJlIHNvbHZlZCBieSBwaW5jdHJsIHN1c3BlbmQgc2V0dGluZ3MsIGJhc2VkIG9u IGdpdmVuIGhhcmR3YXJlDQo+IGNvbmRpdGlvbnMsIHJhdGhlciB0aGFuIHRoZSBkcml2ZXIgZXhw bGljaXRseS4NCj4gDQoNClRoYW5rIHlvdSBmb3IgYWxsIHlvdXIgZXhwbGFuYXRpb24uDQpGaXhl ZCBpbiBuZXh0IHJlbGVhc2UuDQoNCj4gQmVzdCByZWdhcmRzLA0KPiBUb21hc3oNCg0K From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 78F04C433DF for ; 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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-mediatek@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-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=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-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97C34C433DF for ; Wed, 1 Jul 2020 08:00:43 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5CB192074D for ; 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bh=3gRfBix7JRQ6WuG18aqDYF+havpIPRvkgdziQJ/XMHU=; b=hVLKW+fCyLF2nWvvCtLLBF9slJPyX1HaRGHaoeGWdV3NR9pM4Yp+Hl2WUvqTkj/9sFz4M+SgFcSSPTPzfoqmftk3M1WiIQX+pNFWb5MphuSEf86DNgSFY+lWoB49D0e6s58UG9HbqYEMv32DSjuQvh1+J2wKhEQ9WQNCjVpfIlc=; X-UUID: a4c873eb83fd4097a4844c2d545f6e21-20200630 Received: from mtkcas68.mediatek.inc [(172.29.94.19)] by mailgw01.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLS) with ESMTP id 1227687794; 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