Re: [PATCH v2] ACPI: scan: Avoid registering platform devices with resource overlaps

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

On Thu, Aug 06, 2026 at 09:28:03PM +0200, Rafael J. Wysocki wrote:

> If acpi_dev_get_resources() returns overlapping I/O or memory resources,
> the subsequent registration of a platform device will fail with -EBUSY
> due to a resource conflict.  This is reported to happen on Acer Aspire
> ES1-572 [1].
> 
> Avoid that by adjusting resources returned by acpi_dev_get_resources()
> to eliminate partial overlaps between them.
> 
> This has not been regarded as necessary before because putting
> overlapping resources into the _CRS of one device is really pointless,
> but now that the issue has been reported to actually happen in the
> field, it needs to be done.

...

> +static unsigned int acpi_platform_adjust_resources(struct acpi_device *adev,
> +						   struct resource *new_res,
> +						   struct resource *resources,
> +						   unsigned int count)
> +{
> +	unsigned int i;
> +
> +	if (!(new_res->flags & (IORESOURCE_IO | IORESOURCE_MEM)))
> +		return count;
> +
> +	for (i = 0; i < count; ) {
> +		struct resource *res = &resources[i];
> +
> +		if (resource_type(new_res) != resource_type(res) ||
> +		    !resource_overlaps(new_res, res)) {
> +			i++;
> +			continue;
> +		}
> +
> +		dev_info(&adev->dev, "Adjusting %pR for %pR\n", new_res, res);
> +		/*
> +		 * Extend the new resource to include the one that has been processed
> +		 * already.
> +		 */
> +		if (res->start < new_res->start)
> +			new_res->start = res->start;
> +
> +		if (res->end > new_res->end)
> +			new_res->end = res->end;

Can we use resource_union() instead?

> +		/*
> +		 * Eliminate the previously processed resource that has
> +		 * triggered the adjustment because it is not necessary any
> +		 * more.
> +		 */
> +		memmove(res, res + 1, (--count - i) * sizeof(*res));
> +	}
> +
> +	return count;
> +}

-- 
With Best Regards,
Andy Shevchenko