linux-kernel - Re: [PATCH v2] spi: imx: keep dma request disabled before dma transfer setup

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Message-ID: <CAOMZO5DM5NyGdyz4_6WF7qcsMmjAdQvfK0AKxZprUfhC=882pg@mail.gmail.com>
Date: Mon, 27 Oct 2025 09:13:08 -0300
From: Fabio Estevam <festevam@...il.com>
To: carlos.song@....com
Cc: frank.li@....com, broonie@...nel.org, shawnguo@...nel.org, 
	s.hauer@...gutronix.de, kernel@...gutronix.de, linux-spi@...r.kernel.org, 
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] spi: imx: keep dma request disabled before dma
 transfer setup

On Mon, Oct 27, 2025 at 8:04 AM <carlos.song@....com> wrote:
>
> From: Robin Gong <yibin.gong@....com>
>
> Due to a hardware limitation on SDMA event enable (ENBLn), the DMA request
> must remain disabled until the DMA transfer setup is complete.
>
> Refer SDMA 2.6.28 Channel Enable RAM (SDMAARMx_CHNENBLn) section:
>
> "
> It is thus essential for the Arm platform to program them before any DMA
> request is triggered to the SDMA, otherwise an unpredictable combination
> of channels may be started.
> "
>
> SDMA hardware configuration is postponed to transfer phase, so enabling
> the DMA request too early may cause unpredictable channel activation.
> Then keep dma request disabled before dma transfer setup.
>
> Signed-off-by: Carlos Song <carlos.song@....com>
> Signed-off-by: Robin Gong <yibin.gong@....com>

Should this contain a Fixes tag?