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Fri, 19 Jun 2026 04:30:23 -0700 (PDT) Date: Fri, 19 Jun 2026 12:31:24 +0100 From: Nuno =?utf-8?B?U8Oh?= To: Janani Sunil Cc: Jonathan Cameron , Rodrigo Alencar <455.rodrigo.alencar@gmail.com>, Janani Sunil , Lars-Peter Clausen , Michael Hennerich , David Lechner , Nuno =?utf-8?B?U8Oh?= , Andy Shevchenko , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Philipp Zabel , Jonathan Corbet , Shuah Khan , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Mark Brown Subject: Re: [PATCH v3 1/2] dt-bindings: iio: dac: Add AD5529R Message-ID: References: <20260519-ad5529r-driver-v3-0-267c0731aa68@analog.com> <20260519-ad5529r-driver-v3-1-267c0731aa68@analog.com> <25mh6grzh7zh3b4uytcqnusyv5zjuf6ia4if3ce3oqzqz56ehi@le72iqv7ye3d> <603473ac-30e6-45e5-8a3b-c9902715cc9e@gmail.com> <20260614204455.408c4d40@jic23-huawei> <076d7d2d-81a0-49c2-af94-bd65ead66c09@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <076d7d2d-81a0-49c2-af94-bd65ead66c09@gmail.com> On Fri, Jun 19, 2026 at 12:33:11PM +0200, Janani Sunil wrote: > > On 6/14/26 21:44, Jonathan Cameron wrote: > > On Tue, 9 Jun 2026 16:47:23 +0200 > > Janani Sunil wrote: > > > > Hi Jonathan, Rob, Krzysztof, Conor, > > One possible model that would also allow mixing the 12-bit and 16-bit variants would be to treat the parent node > as the shared SPI transport only, and let each dac@N child carry its own compatible. > > Rob, Krzysztof, Conor — wanted to get your input on whether this is an acceptable binding pattern. > > properties: > compatible: > const: adi,ad5529r-bus > > patternProperties: > "^dac@[0-3]$": > type: object > properties: > compatible: > enum: > - adi,ad5529r-16 > - adi,ad5529r-12 > reg: > minimum: 0 > maximum: 3 > > With a DT example such as: > > ad5529r@0 { > compatible = "adi,ad5529r-bus"; > reg = <0>; > > dac@0 { > compatible = "adi,ad5529r-16"; > reg = <0>; > }; > > dac@1 { > compatible = "adi,ad5529r-12"; > reg = <1>; > }; > }; > > The downside is that it introduces adi,ad5529r-bus as a compatible that does not correspond to an actual > standalone device variant - it would require a parent driver to manage the shared SPI transport and enumerate the > child devices. The actual DAC functionality is handled by the matching per-child compatibles(12 or 16 bit). > Is this an acceptable pattern, or is there a preferred way to model this type of addressing scheme? > At some point, I wondered if we can't just have this at spi level? Like (in the simplest terms) a new spi-peripheral property that would allow devices to share the same CS. Then we would need an adi,pin-id kind of property for this device but the bindings would be pretty much as if we only supported one device. I see Mark is already in the loop, maybe he has seen this kind of things before. - Nuno Sá