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([2600:8803:e7e4:1d00:f7b4:dfbd:5110:c59d]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-3196d46d8a6sm356575fac.18.2025.08.30.10.01.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 30 Aug 2025 10:01:43 -0700 (PDT) Message-ID: Date: Sat, 30 Aug 2025 12:01:42 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 08/15] dt-bindings: iio: adc: adi,ad4030: Add 4-lane per channel bus width option To: Marcelo Schmitt , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, devicetree@vger.kernel.org, linux-spi@vger.kernel.org Cc: jic23@kernel.org, Michael.Hennerich@analog.com, nuno.sa@analog.com, eblanc@baylibre.com, andy@kernel.org, corbet@lwn.net, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, broonie@kernel.org, Jonathan.Cameron@huawei.com, andriy.shevchenko@linux.intel.com, ahaslam@baylibre.com, marcelo.schmitt1@gmail.com References: <8011cd2b2f2fe6fd162bc4b4b75ec64255516a87.1756511030.git.marcelo.schmitt@analog.com> Content-Language: en-US From: David Lechner In-Reply-To: <8011cd2b2f2fe6fd162bc4b4b75ec64255516a87.1756511030.git.marcelo.schmitt@analog.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/29/25 7:43 PM, Marcelo Schmitt wrote: > AD4630 has two input channels and each of them can have it's data output in > 4 dedicated lines, resulting in a total of 8 data lines used by the device. > Document the option that specifies the case where AD4630 and similar ADCs > provide data through 8 SPI lines. It is true that there are 8 serial data out lines, but not all lines work the same way. spi-rx-bus-width describes the quad-spi-like lines for sending multiple bits of one word from one channel at the same time. The second set of 4 lines is for sending data from a separate channel at the same time, so it doesn't work with an octal SPI without scrambling data between to two channels. Instead, I am proposing that we consider the second channel (the 2nd set of 4 lines) as a second SPI bus on the same SPI controller. I am currently working on implementing this in the AXI SPI Engine and the AD7380 driver. There is still some HDL work to finalize for this before I can submit it to the mailing lists though. It will use the bindings proposed in [1] rather than spi-rx-bus-width. So we should drop this patch and wait for the other work to be done before supporting reading both channels at the same time on AD4630. [1]: https://lore.kernel.org/linux-spi/20250616220054.3968946-1-sean.anderson@linux.dev/ > > Signed-off-by: Marcelo Schmitt > --- > Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml > index 564b6f67a96e..bee85087a7b2 100644 > --- a/Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml > +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad4030.yaml > @@ -39,7 +39,7 @@ properties: > maximum: 102040816 > > spi-rx-bus-width: > - enum: [1, 2, 4] > + enum: [1, 2, 4, 8] > > vdd-5v-supply: true > vdd-1v8-supply: true