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Thu, 08 Jan 2026 04:42:34 -0800 (PST) Date: Thu, 8 Jan 2026 09:44:20 -0300 From: Marcelo Schmitt To: David Lechner Cc: Mark Brown , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Marcelo Schmitt , Michael Hennerich , Nuno =?iso-8859-1?Q?S=E1?= , Jonathan Cameron , Andy Shevchenko , Sean Anderson , linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org Subject: Re: [PATCH v4 5/9] spi: Documentation: add page on multi-lane support Message-ID: References: <20251219-spi-add-multi-bus-support-v4-0-145dc5204cd8@baylibre.com> <20251219-spi-add-multi-bus-support-v4-5-145dc5204cd8@baylibre.com> 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-Disposition: inline In-Reply-To: <20251219-spi-add-multi-bus-support-v4-5-145dc5204cd8@baylibre.com> Actually, one more thing ... On 12/19, David Lechner wrote: > Add a new page to Documentation/spi/ describing how multi-lane SPI > support works. This is uncommon functionality so it deserves its own > documentation page. > > Signed-off-by: David Lechner > --- ... > +- :c:macro:`SPI_MULTI_BUS_MODE_STRIPE`: Send or receive two different data words > + at the same time, one on each lane. This means that the buffer needs to be > + sized to hold data for all lanes. Data is interleaved in the buffer, with > + the first word corresponding to lane 0, the second to lane 1, and so on. > + Once the last lane is used, the next word in the buffer corresponds to lane > + 0 again. Accordingly, the buffer size must be a multiple of the number of > + lanes. This mode works for both reads and writes. > + > + Example:: > + > + struct spi_transfer xfer = { > + .rx_buf = rx_buf, > + .len = 2, > + .multi_lane_mode = SPI_MULTI_BUS_MODE_STRIPE, > + }; > + > + spi_sync_transfer(spi, &xfer, 1); > + > + Each tx wire has a different data word sent simultaneously:: In this example, the controller is reading data so the rx wires have different data word received? > + > + controller < data bits < peripheral > + ---------- ---------------- ---------- > + SDI 0 0-0-0-1-0-0-0-1 SDO 0 > + SDI 1 1-0-0-0-1-0-0-0 SDO 1 > + > + After the transfer, ``rx_buf[0] == 0x11`` (word from SDO 0) and > + ``rx_buf[1] == 0x88`` (word from SDO 1).