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

[Rafael J. Wysocki (Intel)]

On Fri, Aug 7, 2026 at 11:55 AM Rafael J. Wysocki (Intel)
<rafael@xxxxxxxxxx> wrote:
>
> On Thu, Aug 6, 2026 at 11:23 PM Andy Shevchenko
> <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> >
> > 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?
>
> Not really.

Or maybe.

Let me see if this works.