linux-kernel - Re: [PATCH] spi: cadence-quadspi: Fix clock enable underflows due to runtime PM

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Message-ID: <4d6b857e-4bfe-45ef-a428-6e92f218f0c5@sirena.org.uk>
Date: Thu, 4 Dec 2025 15:11:22 +0000
From: Mark Brown <broonie@...nel.org>
To: Nishanth Menon <nm@...com>
Cc: Francesco Dolcini <francesco@...cini.it>,
	Siddharth Vadapalli <s-vadapalli@...com>,
	Anurag Dutta <a-dutta@...com>, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] spi: cadence-quadspi: Fix clock enable underflows due to
 runtime PM

On Thu, Dec 04, 2025 at 08:05:30AM -0600, Nishanth Menon wrote:

> The clock is already turned off by the runtime-PM suspend callback, so an
> extra clk_disable*_unprepare() is only correct when runtime-PM support is
> not in use.

Right, I'm pretty sure that's where the extra disable is coming from.
The pm_runtime_set_active() further up the function is looking rather
suspect here.

> -	clk_disable_unprepare(cqspi->clk);
> +	/* Runtime-PM suspend already disables the core clock. */
> +	if (ddata && (ddata->quirks & CQSPI_DISABLE_RUNTIME_PM))
> +		clk_disable_unprepare(cqspi->clk);

This will leak the reference if runtime PM isn't enabled unfortunately,
no runtime PM operations will get called.  Life would be vastly simpler
were that mandatory :(

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