From: Rob Herring <robh@kernel.org> To: Peter Rosin <peda@axentia.se> Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Wolfram Sang <wsa@the-dreams.de>, Mark Rutland <mark.rutland@arm.com>, Jonathan Cameron <jic23@kernel.org>, Hartmut Knaack <knaack.h@gmx.de>, Lars-Peter Clausen <lars@metafoo.de>, Peter Meerwald-Stadler <pmeerw@pmeerw.net>, Jonathan Corbet <corbet@lwn.net>, Andrew Morton <akpm@linux-foundation.org>, "linux-i2c@vger.kernel.org" <linux-i2c@vger.kernel.org>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>, "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org> Subject: Re: [PATCH v8 07/12] dt-bindings: i2c: i2c-mux-simple: document i2c-mux-simple bindings Date: Mon, 6 Feb 2017 15:22:17 -0600 [thread overview] Message-ID: <CAL_JsqLfDE-VG01E6ptyL1zXtLDn-zDRmNE9PTsxMqrRzbrXfA@mail.gmail.com> (raw) In-Reply-To: <5dc05e28-45c7-1dfe-3cd2-53e55490b48a@axentia.se> On Fri, Feb 3, 2017 at 2:25 AM, Peter Rosin <peda@axentia.se> wrote: > On 2017-02-02 17:08, Rob Herring wrote: >> On Tue, Jan 31, 2017 at 1:36 AM, Peter Rosin <peda@axentia.se> wrote: >>> If you see this new driver as something that is superseding the existing >>> i2c-mux-gpio driver, I'm sad to inform you that the code is not simply >>> not there. i2c-mux-gpio has acpi support and users may provide platform >>> data from code. The existing i2c-mux-gpio driver also has the below >>> mentioned locking heuristic. Adding all those things to the new driver >>> would make it big and unwieldy and having even more unwanted tentacles >>> into other subsystems. And why should it be only i2c-mux-gpio that is >>> merged into this new i2c-mux driver? Why not implement a mux-pinctrl >>> driver for the new mux subsustem and then merge i2c-mux-pinctrl as well? >>> I say no, that way lies madness. >> >> Sounds like a good idea to me. I'm not saying you need to merge any of >> them right now though (that's Wolfram's call). > > If we're pedantic I probably have some stake in it too, being the i2c-mux > maintainer and all. But, agreed, I arrived quite late to the Linux kernel > party and my opinion might perhaps not carry all that much weight... > >> None of this has anything to do with the binding though. Compatible >> strings should be specific. That's not up for debate. Whether the > > Ok, I'm going to focus on the compatible string for a minute and leave > the implementation details for some other discussion. > >> driver bound to a compatible string is common or specific to that >> compatible string is completely up to the OS. That decision can change >> over time, but the binding should not. > > So, there's the existing compatible "i2c-mux-gpio" ("i2c-gpio-mux" is > wrong) that you seem to suggest is what I should stick to. I object to > that. > > As you say, the bindings and compatible strings should describe hardware, > and you also state they should be specific. I agree. But, why are you > then apparently suggesting (by implication) that for this (hypothetical) > hardware... > > .----. > |SDA0|-----------. > |SCL0|---------. | > | | | | > | | .-------. > | | |adg792a| > | | | | > |ADC0|------|D1 S1A|---- signal A > | | | S1B|---- signal B > | | | S1C|---- signal C > | | | S1D|---- signal D > | | | | > |SDA1|---+--|D2 S2A|---- i2s segment foo A > |SCL1|-. | | S2B|---- i2s segment foo B > '----' | | | S2C|---- i2s segment foo C > | | | S2D|---- i2s segment foo D > | | | | > | '--|D3 S3A|---- i2s segment bar A > | | S3B|---- i2s segment bar B > | | S3C|---- i2s segment bar C > | | S3D|---- i2s segment bar D > | '-------' > | A B C D A B C D (feed SCL1 to each of > | | | | | | | | | the 8 muxed segments) > '------------------+-+-+-+---+-+-+-' > > ...the devicetree should be like below? > > &i2c0 { > mux: mux-controller@50 { > compatible = "adi,adg792a"; > reg = <0x50>; > #mux-control-cells = <1>; > }; > }; > > adc-mux { > compatible = "io-channel-mux"; > io-channels = <&adc 0>; > io-channel-names = "parent"; > > mux-controls = <&mux 0>; > > ... > }; > > i2c-mux-foo { > compatible = "i2c-mux-gpio"; > i2c-parent = <&i2c1>; > > mux-controls = <&mux 1>; > > ... > }; > > i2c-mux-bar { > compatible = "i2c-mux-gpio"; > i2c-parent = <&i2c1>; > > mux-controls = <&mux 2>; > > ... > }; > > There must be some disconnect, because those "i2c-mux-gpio" compatible > strings are just dead wrong. There simply are no gpio pins involved at > all and that "gpio" suffix is just totally out of place. Indeed. In the above case, that makes no sense. > So, since you are not happy with "i2c-mux-simple", "i2c-mux-generic" or > "i2c-mux" that I have suggested, can you please come up with something > that is good enough for the above? Let's go with just "i2c-mux". I've got nothing better and simple or generic doesn't add anything. Rob
WARNING: multiple messages have this Message-ID (diff)
From: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> To: Peter Rosin <peda-koto5C5qi+TLoDKTGw+V6w@public.gmane.org> Cc: "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Wolfram Sang <wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org>, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>, Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Hartmut Knaack <knaack.h-Mmb7MZpHnFY@public.gmane.org>, Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>, Peter Meerwald-Stadler <pmeerw-jW+XmwGofnusTnJN9+BGXg@public.gmane.org>, Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org> Subject: Re: [PATCH v8 07/12] dt-bindings: i2c: i2c-mux-simple: document i2c-mux-simple bindings Date: Mon, 6 Feb 2017 15:22:17 -0600 [thread overview] Message-ID: <CAL_JsqLfDE-VG01E6ptyL1zXtLDn-zDRmNE9PTsxMqrRzbrXfA@mail.gmail.com> (raw) In-Reply-To: <5dc05e28-45c7-1dfe-3cd2-53e55490b48a-koto5C5qi+TLoDKTGw+V6w@public.gmane.org> On Fri, Feb 3, 2017 at 2:25 AM, Peter Rosin <peda-koto5C5qi+TLoDKTGw+V6w@public.gmane.org> wrote: > On 2017-02-02 17:08, Rob Herring wrote: >> On Tue, Jan 31, 2017 at 1:36 AM, Peter Rosin <peda-koto5C5qi+TLoDKTGw+V6w@public.gmane.org> wrote: >>> If you see this new driver as something that is superseding the existing >>> i2c-mux-gpio driver, I'm sad to inform you that the code is not simply >>> not there. i2c-mux-gpio has acpi support and users may provide platform >>> data from code. The existing i2c-mux-gpio driver also has the below >>> mentioned locking heuristic. Adding all those things to the new driver >>> would make it big and unwieldy and having even more unwanted tentacles >>> into other subsystems. And why should it be only i2c-mux-gpio that is >>> merged into this new i2c-mux driver? Why not implement a mux-pinctrl >>> driver for the new mux subsustem and then merge i2c-mux-pinctrl as well? >>> I say no, that way lies madness. >> >> Sounds like a good idea to me. I'm not saying you need to merge any of >> them right now though (that's Wolfram's call). > > If we're pedantic I probably have some stake in it too, being the i2c-mux > maintainer and all. But, agreed, I arrived quite late to the Linux kernel > party and my opinion might perhaps not carry all that much weight... > >> None of this has anything to do with the binding though. Compatible >> strings should be specific. That's not up for debate. Whether the > > Ok, I'm going to focus on the compatible string for a minute and leave > the implementation details for some other discussion. > >> driver bound to a compatible string is common or specific to that >> compatible string is completely up to the OS. That decision can change >> over time, but the binding should not. > > So, there's the existing compatible "i2c-mux-gpio" ("i2c-gpio-mux" is > wrong) that you seem to suggest is what I should stick to. I object to > that. > > As you say, the bindings and compatible strings should describe hardware, > and you also state they should be specific. I agree. But, why are you > then apparently suggesting (by implication) that for this (hypothetical) > hardware... > > .----. > |SDA0|-----------. > |SCL0|---------. | > | | | | > | | .-------. > | | |adg792a| > | | | | > |ADC0|------|D1 S1A|---- signal A > | | | S1B|---- signal B > | | | S1C|---- signal C > | | | S1D|---- signal D > | | | | > |SDA1|---+--|D2 S2A|---- i2s segment foo A > |SCL1|-. | | S2B|---- i2s segment foo B > '----' | | | S2C|---- i2s segment foo C > | | | S2D|---- i2s segment foo D > | | | | > | '--|D3 S3A|---- i2s segment bar A > | | S3B|---- i2s segment bar B > | | S3C|---- i2s segment bar C > | | S3D|---- i2s segment bar D > | '-------' > | A B C D A B C D (feed SCL1 to each of > | | | | | | | | | the 8 muxed segments) > '------------------+-+-+-+---+-+-+-' > > ...the devicetree should be like below? > > &i2c0 { > mux: mux-controller@50 { > compatible = "adi,adg792a"; > reg = <0x50>; > #mux-control-cells = <1>; > }; > }; > > adc-mux { > compatible = "io-channel-mux"; > io-channels = <&adc 0>; > io-channel-names = "parent"; > > mux-controls = <&mux 0>; > > ... > }; > > i2c-mux-foo { > compatible = "i2c-mux-gpio"; > i2c-parent = <&i2c1>; > > mux-controls = <&mux 1>; > > ... > }; > > i2c-mux-bar { > compatible = "i2c-mux-gpio"; > i2c-parent = <&i2c1>; > > mux-controls = <&mux 2>; > > ... > }; > > There must be some disconnect, because those "i2c-mux-gpio" compatible > strings are just dead wrong. There simply are no gpio pins involved at > all and that "gpio" suffix is just totally out of place. Indeed. In the above case, that makes no sense. > So, since you are not happy with "i2c-mux-simple", "i2c-mux-generic" or > "i2c-mux" that I have suggested, can you please come up with something > that is good enough for the above? Let's go with just "i2c-mux". I've got nothing better and simple or generic doesn't add anything. Rob
next prev parent reply other threads:[~2017-02-06 21:22 UTC|newest] Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-01-18 15:57 [PATCH v8 00/12] mux controller abstraction and iio/i2c muxes Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-18 15:57 ` [PATCH v8 01/12] devres: trivial whitespace fix Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-18 15:57 ` [PATCH v8 02/12] dt-bindings: document devicetree bindings for mux-controllers and mux-gpio Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-27 17:49 ` Rob Herring 2017-01-27 17:49 ` Rob Herring 2017-01-27 18:57 ` Peter Rosin 2017-01-27 18:57 ` Peter Rosin 2017-01-18 15:57 ` [PATCH v8 03/12] mux: minimal mux subsystem and gpio-based mux controller Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-18 15:57 ` [PATCH v8 04/12] iio: inkern: api for manipulating ext_info of iio channels Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-18 15:57 ` [PATCH v8 05/12] dt-bindings: iio: io-channel-mux: document io-channel-mux bindings Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-27 19:12 ` Rob Herring 2017-01-18 15:57 ` [PATCH v8 06/12] iio: multiplexer: new iio category and iio-mux driver Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-18 15:57 ` [PATCH v8 07/12] dt-bindings: i2c: i2c-mux-simple: document i2c-mux-simple bindings Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-27 19:39 ` Rob Herring 2017-01-28 22:42 ` Peter Rosin 2017-01-28 22:42 ` Peter Rosin 2017-01-30 17:20 ` Rob Herring 2017-01-30 17:20 ` Rob Herring 2017-01-31 7:36 ` Peter Rosin 2017-01-31 7:36 ` Peter Rosin 2017-02-02 16:08 ` Rob Herring 2017-02-03 8:25 ` Peter Rosin 2017-02-06 21:22 ` Rob Herring [this message] 2017-02-06 21:22 ` Rob Herring 2017-01-18 15:57 ` [PATCH v8 08/12] i2c: i2c-mux-simple: new driver Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-18 15:57 ` [PATCH v8 09/12] dt-bindings: mux-adg792a: document devicetree bindings for ADG792A/G mux Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-27 19:50 ` Rob Herring 2017-01-27 22:09 ` Peter Rosin 2017-01-27 22:09 ` Peter Rosin 2017-01-28 10:34 ` Peter Meerwald-Stadler 2017-01-28 10:34 ` Peter Meerwald-Stadler 2017-01-28 11:40 ` Jonathan Cameron 2017-01-18 15:57 ` [PATCH v8 10/12] mux: adg792a: add mux controller driver for ADG792A/G Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-18 15:57 ` [PATCH v8 11/12] dt-bindings: simplified bindings for single-user gpio mux Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-18 15:57 ` [PATCH v8 12/12] mux: support " Peter Rosin 2017-01-18 15:57 ` Peter Rosin 2017-01-22 13:30 ` Jonathan Cameron 2017-01-22 13:30 ` Jonathan Cameron 2017-01-23 10:24 ` Peter Rosin 2017-01-27 15:52 ` Rob Herring 2017-01-30 8:02 ` Peter Rosin 2017-01-30 8:02 ` Peter Rosin
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