Question of " 202317a : ACPI / scan: Add acpi_device objects for all device nodes in the namespace" commit

[Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>]

Hi Rafael,

Why is _SUN method decoded and the sun sysfs created even if _STA reports
that the device is not present and not functional?

By this commit, "202317a : ACPI / scan: Add acpi_device objects for all
device nodes in the namespace", all device nodes in the namespace are
shown under /sys/bus/acpi/devices direcotry even if the devices are not
present and not functional.

But ACPI specification says against return value information of _STA:
A device can only decode its hardware resources if both bits 0 and 1 are set.
If the device is not present (bit 0 cleared) or not enabled (bit 1 cleared),
then the device must not decode its resources.

In my understanding, when the device is not present and not functional,
_SUN of the device must not be decoded. Is my understanding worng?

In our box, when the device is not present and not functional, _SUN method
of the device returns wrong value. And the values is cached to
acpi_device->pnp.sun. So when hot adding the device and changing _SUN value,
the information is not reflected to acpi_device->pnp.sun.

I think the issue is solved by not caching sun value. But at first, I want
to know whether current implementation is correct or not.

Thanks,
Yasuaki Ishimatsu