linux-kernel - Re: [PATCH 3/4] spi: stm32: properly fail on dma_request

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Message-ID: <20251218083840.GA1530150@gnbcxd0016.gnb.st.com>
Date: Thu, 18 Dec 2025 09:38:40 +0100
From: Alain Volmat <alain.volmat@...s.st.com>
To: Mark Brown <broonie@...nel.org>
CC: Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue
	<alexandre.torgue@...s.st.com>,
        Rob Herring <robh@...nel.org>,
        "Krzysztof
 Kozlowski" <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>, <linux-spi@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH 3/4] spi: stm32: properly fail on dma_request_chan error

Hi Mark,

On Thu, Dec 18, 2025 at 08:00:57AM +0000, Mark Brown wrote:
> On Wed, Dec 17, 2025 at 10:51:33PM +0100, Alain Volmat wrote:
> > Correct handling of the dma_request_chan call in order to avoid
> > misleading warn message if no DMA is provided within the device-tree
> > and moreover fail if dma_request_chan has returned a valid error.
> 
> Bug fixes should go at the start of serieses to avoid spurious
> dependencies on new or cleanup changes.

Actually I wasn't thinking about requiring this commit to go into
stable branches. Without commit, the driver will still work even if
there is an issue to request a dma channel since it will fallback to
interrupt based transfers.
This commit makes the error visible now, ensuring that if the
device-tree indicates that a DMA should be used, it will either be used
or probe will fail.

Alain