From: Marco Felsch <m.felsch@pengutronix.de> To: Robert Foss <robert.foss@linaro.org> Cc: Dongchun Zhu <dongchun.zhu@mediatek.com>, Tomasz Figa <tfiga@chromium.org>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Sakari Ailus <sakari.ailus@iki.fi>, Maxime Ripard <maxime@cerno.tech>, linux-media <linux-media@vger.kernel.org>, "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" <devicetree@vger.kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" <linux-arm-kernel@lists.infradead.org>, Fabio Estevam <festevam@gmail.com>, Ben Kao <ben.kao@intel.com>, Maxime Ripard <mripard@kernel.org> Subject: Re: [PATCH v10 1/3] media: dt-bindings: ov8856: Document YAML bindings Date: Wed, 6 May 2020 14:26:20 +0200 [thread overview] Message-ID: <20200506122620.GN18755@pengutronix.de> (raw) In-Reply-To: <CAG3jFyvo3gmO3zLRUKQEdgRkmzvvvMTzDKV-LZAeKYFdOfCnEw@mail.gmail.com> On 20-05-06 13:29, Robert Foss wrote: > Hey Dongchun, > > Thanks for having a look at this series. > > > > +examples: > > > + - | > > > + #include <dt-bindings/gpio/gpio.h> > > > + > > > + i2c { > > > + #address-cells = <1>; > > > + #size-cells = <0>; > > > + > > > + ov8856: camera@10 { > > > + compatible = "ovti,ov8856"; > > > + reg = <0x10>; > > > + > > > + reset-gpios = <&pio 111 GPIO_ACTIVE_LOW>; > > > > Apologies for missing to follow the earlier discussion related to this. > > I noticed the GPIO flag para and __ov8856_power_on() are aligned using > > ACTIVE_LOW. > > > > But from the datasheet, XSHUTDN pin is active-high for OV8856. > > It means devm_gpiod_get API (in probe func) should use GPIOD_OUT_LOW to > > initialize the GPIO as output with a value of 0. > > Otherwise it should use GPIOD_OUT_HIGH. > > > > There is one case for GPIO_ACTIVE_LOW setting: > > https://patchwork.linuxtv.org/patch/63460/ > > https://patchwork.linuxtv.org/patch/63461/ > > We went back and forth about this a few times, and I switched to this > gpio setting after having worked through the device probing reset gpio > toggling. Semantically it seemed easier to understand in the driver, > since the gpio is called reset and not !shutdown. IMHO you can keep your version. DTs are part of the system integration. What if one system has a invert logic infront of the gpio input.. The system integrator needs to read and to understand the schematic correctly to pick the correct value. > Looking into devm_gpiod_get_optional(), the flag argument > GPIOD_OUT_LOW or HIGH for that matter is actually not used initialize The good think about gpiod is that it care about logic values not physical/electrical values. If you set GPIOD_OUT_HIGH then the reset is asserted, whatever asserted means electrical. Regards, Marco > the output, but only used for an exclusivity check. > https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib-devres.c#L109 > > If you prefer, I can invert the logic again. To me making the reset > gpio active resulting in the device being actually reset seems like > the most intuitive and easy to understand option. > The different OmniVision drivers seem to have different approaches to > this. The ov9640 driver for example is doing what this series > currently is doing. > > > > > Sakari, Tomasz, am I right? > > > > > + pinctrl-names = "default"; > > > + pinctrl-0 = <&clk_24m_cam>; > > > + > > > + clocks = <&cam_osc>; > > > + clock-names = "xvclk"; > > > + clock-frequency = <19200000>; > > > + > > > + avdd-supply = <&mt6358_vcama2_reg>; > > > + dvdd-supply = <&mt6358_vcamd_reg>; > > > + dovdd-supply = <&mt6358_vcamio_reg>; > > > + > > > + port { > > > + wcam_out: endpoint { > > > + remote-endpoint = <&mipi_in_wcam>; > > > + data-lanes = <1 2 3 4>; > > > + link-frequencies = /bits/ 64 <360000000>; > > > + }; > > > + }; > > > + }; > > > + }; > > > +... > > > \ No newline at end of file > > > diff --git a/MAINTAINERS b/MAINTAINERS > > > index 26f281d9f32a..84b262afd13d 100644 > > > --- a/MAINTAINERS > > > +++ b/MAINTAINERS > > > @@ -12489,6 +12489,7 @@ L: linux-media@vger.kernel.org > > > S: Maintained > > > T: git git://linuxtv.org/media_tree.git > > > F: drivers/media/i2c/ov8856.c > > > +F: Documentation/devicetree/bindings/media/i2c/ov8856.yaml > > > > > > > Had you run parse-maintainers.pl? > > The new item is supposed to be arranged in alphabetical order. > > No, I have not. But upon running it now, it doesn't make suggest any > changes. But let me order the files manually in the next revision. > > However, I noticed I removed the wrong person from the maintainers > file in this revision. > So, I'll correct that and add you Dongchun as the maintainer if that's ok. > > > > > > OMNIVISION OV9640 SENSOR DRIVER > > > M: Petr Cvek <petrcvekcz@gmail.com> > > > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
WARNING: multiple messages have this Message-ID (diff)
From: Marco Felsch <m.felsch@pengutronix.de> To: Robert Foss <robert.foss@linaro.org> Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" <devicetree@vger.kernel.org>, Maxime Ripard <maxime@cerno.tech>, linux-kernel <linux-kernel@vger.kernel.org>, Maxime Ripard <mripard@kernel.org>, Tomasz Figa <tfiga@chromium.org>, Ben Kao <ben.kao@intel.com>, Sakari Ailus <sakari.ailus@iki.fi>, Dongchun Zhu <dongchun.zhu@mediatek.com>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Fabio Estevam <festevam@gmail.com>, "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" <linux-arm-kernel@lists.infradead.org>, linux-media <linux-media@vger.kernel.org> Subject: Re: [PATCH v10 1/3] media: dt-bindings: ov8856: Document YAML bindings Date: Wed, 6 May 2020 14:26:20 +0200 [thread overview] Message-ID: <20200506122620.GN18755@pengutronix.de> (raw) In-Reply-To: <CAG3jFyvo3gmO3zLRUKQEdgRkmzvvvMTzDKV-LZAeKYFdOfCnEw@mail.gmail.com> On 20-05-06 13:29, Robert Foss wrote: > Hey Dongchun, > > Thanks for having a look at this series. > > > > +examples: > > > + - | > > > + #include <dt-bindings/gpio/gpio.h> > > > + > > > + i2c { > > > + #address-cells = <1>; > > > + #size-cells = <0>; > > > + > > > + ov8856: camera@10 { > > > + compatible = "ovti,ov8856"; > > > + reg = <0x10>; > > > + > > > + reset-gpios = <&pio 111 GPIO_ACTIVE_LOW>; > > > > Apologies for missing to follow the earlier discussion related to this. > > I noticed the GPIO flag para and __ov8856_power_on() are aligned using > > ACTIVE_LOW. > > > > But from the datasheet, XSHUTDN pin is active-high for OV8856. > > It means devm_gpiod_get API (in probe func) should use GPIOD_OUT_LOW to > > initialize the GPIO as output with a value of 0. > > Otherwise it should use GPIOD_OUT_HIGH. > > > > There is one case for GPIO_ACTIVE_LOW setting: > > https://patchwork.linuxtv.org/patch/63460/ > > https://patchwork.linuxtv.org/patch/63461/ > > We went back and forth about this a few times, and I switched to this > gpio setting after having worked through the device probing reset gpio > toggling. Semantically it seemed easier to understand in the driver, > since the gpio is called reset and not !shutdown. IMHO you can keep your version. DTs are part of the system integration. What if one system has a invert logic infront of the gpio input.. The system integrator needs to read and to understand the schematic correctly to pick the correct value. > Looking into devm_gpiod_get_optional(), the flag argument > GPIOD_OUT_LOW or HIGH for that matter is actually not used initialize The good think about gpiod is that it care about logic values not physical/electrical values. If you set GPIOD_OUT_HIGH then the reset is asserted, whatever asserted means electrical. Regards, Marco > the output, but only used for an exclusivity check. > https://elixir.bootlin.com/linux/latest/source/drivers/gpio/gpiolib-devres.c#L109 > > If you prefer, I can invert the logic again. To me making the reset > gpio active resulting in the device being actually reset seems like > the most intuitive and easy to understand option. > The different OmniVision drivers seem to have different approaches to > this. The ov9640 driver for example is doing what this series > currently is doing. > > > > > Sakari, Tomasz, am I right? > > > > > + pinctrl-names = "default"; > > > + pinctrl-0 = <&clk_24m_cam>; > > > + > > > + clocks = <&cam_osc>; > > > + clock-names = "xvclk"; > > > + clock-frequency = <19200000>; > > > + > > > + avdd-supply = <&mt6358_vcama2_reg>; > > > + dvdd-supply = <&mt6358_vcamd_reg>; > > > + dovdd-supply = <&mt6358_vcamio_reg>; > > > + > > > + port { > > > + wcam_out: endpoint { > > > + remote-endpoint = <&mipi_in_wcam>; > > > + data-lanes = <1 2 3 4>; > > > + link-frequencies = /bits/ 64 <360000000>; > > > + }; > > > + }; > > > + }; > > > + }; > > > +... > > > \ No newline at end of file > > > diff --git a/MAINTAINERS b/MAINTAINERS > > > index 26f281d9f32a..84b262afd13d 100644 > > > --- a/MAINTAINERS > > > +++ b/MAINTAINERS > > > @@ -12489,6 +12489,7 @@ L: linux-media@vger.kernel.org > > > S: Maintained > > > T: git git://linuxtv.org/media_tree.git > > > F: drivers/media/i2c/ov8856.c > > > +F: Documentation/devicetree/bindings/media/i2c/ov8856.yaml > > > > > > > Had you run parse-maintainers.pl? > > The new item is supposed to be arranged in alphabetical order. > > No, I have not. But upon running it now, it doesn't make suggest any > changes. But let me order the files manually in the next revision. > > However, I noticed I removed the wrong person from the maintainers > file in this revision. > So, I'll correct that and add you Dongchun as the maintainer if that's ok. > > > > > > OMNIVISION OV9640 SENSOR DRIVER > > > M: Petr Cvek <petrcvekcz@gmail.com> > > > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-05-06 12:26 UTC|newest] Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-05-05 10:01 [PATCH v7 0/3] media: ov8856: Add devicetree support Robert Foss 2020-05-05 10:01 ` Robert Foss 2020-05-05 10:01 ` [PATCH v10 1/3] media: dt-bindings: ov8856: Document YAML bindings Robert Foss 2020-05-05 10:01 ` Robert Foss 2020-05-05 11:47 ` Dongchun Zhu 2020-05-05 11:47 ` Dongchun Zhu 2020-05-06 11:29 ` Robert Foss 2020-05-06 11:29 ` Robert Foss 2020-05-06 12:26 ` Marco Felsch [this message] 2020-05-06 12:26 ` Marco Felsch 2020-05-05 15:48 ` Rob Herring 2020-05-05 15:48 ` Rob Herring 2020-05-05 15:49 ` Rob Herring 2020-05-05 15:49 ` Rob Herring 2020-05-06 11:30 ` Robert Foss 2020-05-06 11:30 ` Robert Foss 2020-05-05 10:01 ` [PATCH v7 2/3] media: ov8856: Add devicetree support Robert Foss 2020-05-05 10:01 ` Robert Foss 2020-05-05 10:16 ` Marco Felsch 2020-05-05 10:16 ` Marco Felsch 2020-05-06 14:43 ` Robert Foss 2020-05-06 14:43 ` Robert Foss 2020-05-07 8:06 ` Kao, Ben 2020-05-07 8:06 ` Kao, Ben 2020-05-07 8:21 ` Marco Felsch 2020-05-07 8:21 ` Marco Felsch 2020-05-08 9:45 ` Kao, Ben 2020-05-08 9:45 ` Kao, Ben 2020-05-07 8:39 ` Robert Foss 2020-05-07 8:39 ` Robert Foss 2020-05-08 9:50 ` Kao, Ben 2020-05-08 9:50 ` Kao, Ben 2020-05-05 10:01 ` [PATCH v7 3/3] media: ov8856: Implement sensor module revision identification Robert Foss 2020-05-05 10:01 ` Robert Foss 2020-05-05 10:17 ` Marco Felsch 2020-05-05 10:17 ` Marco Felsch 2020-05-06 14:48 ` Robert Foss 2020-05-06 14:48 ` Robert Foss
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