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([2600:8803:e7e4:1d00:ee1a:f057:94fa:9a73]) by smtp.gmail.com with ESMTPSA id 5614622812f47-435ed1bfb0bsm1759838b6e.22.2025.08.18.08.22.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 18 Aug 2025 08:22:43 -0700 (PDT) Message-ID: <0b9a3b8b-11d5-4722-a7ea-e80d893bc209@baylibre.com> Date: Mon, 18 Aug 2025 10:22:41 -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 v2 1/9] dt-bindings: spi: Add spi-buses property To: Miquel Raynal Cc: Sean Anderson , Mark Brown , Michal Simek , linux-spi@vger.kernel.org, Jinjie Ruan , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Amit Kumar Mahapatra References: <20250616220054.3968946-1-sean.anderson@linux.dev> <20250616220054.3968946-2-sean.anderson@linux.dev> <87frdp119x.fsf@bootlin.com> Content-Language: en-US From: David Lechner In-Reply-To: <87frdp119x.fsf@bootlin.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 8/18/25 3:28 AM, Miquel Raynal wrote: > Hello, > >>> + spi-buses: >>> + description: >>> + Array of bus numbers that describes which SPI buses of the controller are >>> + connected to the peripheral. This only applies to peripherals connected >>> + to specialized SPI controllers that have multiple SPI buses on a single >>> + controller. >>> + $ref: /schemas/types.yaml#/definitions/uint32-array >>> + minItems: 1 > >> >> Finally have some hardware to test this series with using 2 or 4 buses. > > Out of curiosity, what is the practical use case and intended benefit? > Maybe an example of such device and an explanation of how useful this is > would be welcome, as it does not seem to fit the initial spi idea > (which has been greatly "improved", not saying it is bad, just unusual). > > Thanks, > Miquèl >From my side, I am working on supporting complex analog-digital converters. There are many of these that contain multiple converters in a single chip and have multiple serial data lines so that the data from each converter can be read on a separate serial line to speed up throughput. And in some cases multiple chips are also used in parallel to the same effect. I.e. all chips share the same conversion trigger and we want to read back the data from all chips at the same time to get max throughput.