Re: [PATCH v17 2/6] spi: pxa2xx: introduce clock enable and disable helper functions

[Mark Brown <broonie@debian.org>]

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On Thu, Oct 01, 2026 at 12:06:25AM +0800, Shih-Yuan Lee wrote:
> The driver enables and disables the SOC clock during probe, teardown,
> and power management callbacks. Directly calling clk_disable_unprepare()
> when the clock is already disabled—such as when removing a device that
> is runtime-suspended—causes an unbalanced clock disable warning from the
> Common Clock Framework.

> Introduce pxa2xx_spi_clk_enable() and pxa2xx_spi_clk_disable() helper
> functions that track the clock state with a 'clk_enabled' boolean flag
> protected by a 'clk_lock' mutex in struct driver_data. These helpers
> make clock toggling idempotent: repeated enable or disable invocations
> are safe no-ops serialized by clk_lock.

What problem is this solving?  Usually if something is dropping a
reference to a shared resource like a clock without knowing if it took
it then whatever else might have been using the resource is going to be
broken when the clock suddenly vanishes underneath it.  If we are
coordinating properly we shouldn't need the flag, the refcount should be
good enough.


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