Re: [PATCH v3 6/9] i2c: of-prober: Defer regulator_disable() on successful probe in simple helper

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Tue, Jul 21, 2026 at 03:52:20PM +0800, Chen-Yu Tsai wrote:
> When a I2C component is found, it's device node is immediately enabled.
> This triggers device creation and driver binding. The prober will hold
> the regulator enable reference across this part. If the driver probes
> synchronously, then it happens within this window. On the other hand,
> if the driver probes asynchronously, there is high chance that it
> happens after the prober's cleanup function was called, in which case
> the regulator would have been disabled when the driver's probe function
> is called. This would then require the driver to wait 100 ms for the
> hardware to reinitialize, even if the probe function was just a split
> second late and the regulator was disabled a few milliseconds ago.
> 
> Recently, some of the drivers for the component that are targeted by the
> I2C OF component prober gained the ability to skip waiting for hardware
> initialization if the regulator was left enabled. This happens when the
> PMIC has them on by default, or if the component prober left them on
> after probing the component.
> 
> Wait a bit of time before dropping the enable refcount on our end so
> that the actual driver has the opportunity to catch and increase the
> refcount on their end. The 100 ms delay was arbitrarily chosen.

...

> +	/*
> +	 * Wait a bit of time for async drivers to probe and increase the
> +	 * regulator enable count. This allows the drivers to check and
> +	 * skip waiting for re-initialization.
> +	 */
> +	if (defer_disable) {
> +		dev_dbg(dev, "Deferring regulator disable\n");
> +		msleep(100);

How was this value chosen?

> +	}

-- 
With Best Regards,
Andy Shevchenko