From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D2A91DDA0; Sun, 26 Nov 2023 16:04:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MPCc7s3s" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4FACEC433C7; Sun, 26 Nov 2023 16:04:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701014688; bh=juZpsIMH+zxndA5/oqXyf6KAF1d5Vbdex0YVpHNxFtg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MPCc7s3sMuYrw2qSU3ehirBXCceb+Zc90kY3gwhzjjR+P0ylUyt5udZAKW7GoOy9M wGtg5u2BuYdWwoHbXpTtF1Wu8E4O/Z9S72LP0R4Z0zmHYOSbAeCEpuPF8HSDtfYNZr YnPROqMvDbjjS4XIZmBohZBtm58uHVUfM1RCBjtkVCNTNJ8srAqkVFtDR45d6ErW/I Kz7fWIExR/f2eHHVsj7ts8L7x5Bepurm/ivk0hso233j7Y54y8r4CCpFSzRHpoNPW8 Wv49cTpyWZsBGMoQhAqcNAPFnVG2SsxfSt8sahOiz8q3b4CcHVVKg2UPZzQtt+Kvfk /rxGOnAMw1U9w== Date: Sun, 26 Nov 2023 16:04:38 +0000 From: Jonathan Cameron To: Conor Dooley Cc: Krzysztof Kozlowski , marius.cristea@microchip.com, lars@metafoo.de, robh+dt@kernel.org, jdelvare@suse.com, linux@roeck-us.net, linux-hwmon@vger.kernel.org, krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/2] dt-bindings: iio: adc: adding support for PAC193X Message-ID: <20231126160438.01ff57d7@jic23-huawei> In-Reply-To: <20231126-nineteen-clumsy-701ac4145ba8@spud> References: <20231115134453.6656-1-marius.cristea@microchip.com> <20231115134453.6656-2-marius.cristea@microchip.com> <20231116-channel-variety-cc7c262924ad@squawk> <20231125194754.304523e6@jic23-huawei> <20231126-nineteen-clumsy-701ac4145ba8@spud> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 26 Nov 2023 11:24:56 +0000 Conor Dooley wrote: > On Sat, Nov 25, 2023 at 07:47:54PM +0000, Jonathan Cameron wrote: > > On Thu, 16 Nov 2023 18:21:33 +0000 > > Conor Dooley wrote: > > > On Thu, Nov 16, 2023 at 04:01:43PM +0100, Krzysztof Kozlowski wrote: > > > > On 15/11/2023 14:44, marius.cristea@microchip.com wrote: > > > > > From: Marius Cristea > > > > > > +patternProperties: > > > > > + "^channel@[1-4]+$": > > > > > + type: object > > > > > + $ref: adc.yaml > > > > > + description: Represents the external channels which are connected to the ADC. > > > > > + > > > > > + properties: > > > > > + reg: > > > > > + items: > > > > > + minimum: 1 > > > > > + maximum: 4 > > > > > + > > > > > + shunt-resistor-micro-ohms: > > > > > + description: | > > > > > + Value in micro Ohms of the shunt resistor connected between > > > > > + the SENSE+ and SENSE- inputs, across which the current is measured. Value > > > > > + is needed to compute the scaling of the measured current. > > > > > + > > > > > + required: > > > > > + - reg > > > > > + - shunt-resistor-micro-ohms > > > > > + > > > > > + unevaluatedProperties: false > > > > > + > > > > > +required: > > > > > + - compatible > > > > > + - reg > > > > > + - "#address-cells" > > > > > + - "#size-cells" > > > > > + > > > > > +allOf: > > > > > + - if: > > > > > + properties: > > > > > + compatible: > > > > > + contains: > > > > > + const: interrupts > > > > > > > > > > > > I don't understand what do you want to say here. I am also 100% sure you > > > > did not test it on a real case (maybe example passes but nothing more). > > > > > > As far as I understand, the same pin on the device is used for both an > > > output or an input depending on the configuration. As an input, it is > > > the "slow-io" control, and as an output it is an interrupt. > > > I think Marius is trying to convey that either this pin can be in > > > exclusively one state or another. > > > > > > _However_ I am not sure that that is really the right thing to do - they > > > might well be mutually exclusive modes, but I think the decision can be > > > made at runtime, rather than at devicetree creation time. Say for > > > example the GPIO controller this is connected to is capable of acting as > > > an interrupt controller. Unless I am misunderstanding the runtime > > > configurability of this hardware, I think it is possible to actually > > > provide a "slow-io-gpios" and an interrupt property & let the operating > > > system decide at runtime which mode it wants to work in. > > > > I'll admit I've long forgotten what was going on here, but based just on > > this bit of text I agree. There is nothing 'stopping' us having a pin > > uses as either / or / both interrupt and gpio. > > > > It'll be a bit messy to support in the driver as IIRC there are some sanity > > checks that limit combinations on IRQs and output GPIOS. Can't remember > > how bad the dance to navigate it safely is. > > > > First version I'd just say pick one option if both are provided and > > don't support configuring it at runtime. > > Just to be clear, you are suggesting having the > "microchip,slow-io-gpios" and "interrupts" properties in the binding, > but the driver will just (for example) put that pin into alert mode > always & leave it there? Yes. > If that is what you are suggesting, that seems pragmatic to me. If a use case to do something else comes along later, then we can be smarter, but I'd like to keep it simple initially at least. Jonathan > > Cheers, > Conor. >