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Wed, 25 Jun 2025 06:01:09 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-spi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: T588a20d0ffbb3e40 Date: Wed, 25 Jun 2025 12:00:38 +0200 From: "Arnd Bergmann" To: "James Clark" , "Frank Li" Cc: "Vladimir Oltean" , "Mark Brown" , "Vladimir Oltean" , "Larisa Grigore" , "Christoph Hellwig" , linux-spi@vger.kernel.org, imx@lists.linux.dev, linux-kernel@vger.kernel.org Message-Id: <0f904f12-295c-48fe-96c7-c64c461cdbbd@app.fastmail.com> In-Reply-To: <0c6c78da-575a-4d29-a79a-3903aa801b42@linaro.org> References: <20250624-james-nxp-spi-dma-v3-0-e7d574f5f62c@linaro.org> <20250624-james-nxp-spi-dma-v3-3-e7d574f5f62c@linaro.org> <290fc244-e88f-47a3-8dd3-0ec27eb5c60b@app.fastmail.com> <0c6c78da-575a-4d29-a79a-3903aa801b42@linaro.org> Subject: Re: [PATCH v3 3/6] spi: spi-fsl-dspi: Stub out DMA functions Content-Type: text/plain Content-Transfer-Encoding: 7bit On Wed, Jun 25, 2025, at 11:19, James Clark wrote: > On 24/06/2025 6:16 pm, Arnd Bergmann wrote: >> On Tue, Jun 24, 2025, at 18:29, Frank Li wrote: > >> It would also be simpler to enforce this in Kconfig if we only >> care about users that use the DMA support. > > But most of the devices supported by the driver don't do any DMA. That > was the reason to stub them out rather than add the Kconfig depends. Ah right. So even when running on SoCs that have a DMA engine, you can end up not using it? In this case you could have an extra Kconfig symbol to configure DMA support for this driver and use that in the source code: config SPI_FSL_DSPI_DMA bool "Use DMA engine for offloading Freescale DSPI transfers" depends on SPI_FSL_DSPI && DMA_ENGINE help .... Arnd