Re: ACPI vs Device Tree - moving forward

From: Guenter Roeck
Date: Sat Aug 24 2013 - 01:30:58 EST


On 08/23/2013 09:51 PM, Matthew Garrett wrote:
On Fri, Aug 23, 2013 at 09:45:10PM -0700, Guenter Roeck wrote:

"What happens when you have an ACPI device that contains an interrupt in
_CRS and contains a different interrupt in an embedded FDT block?"

Does the situation occur today, ie does it ever happen that one interrupt
for a device is specified (if that is the correct term) in _CRS and
another by some other means ?

The only case I can think of is PCI, where we ignored the ACPI-provided
resources until fairly recently. That was a somewhat reasonable thing to
do, since the hardware still had to support pre-ACPI operating systems
and so the non-ACPI information sources were typically correct.

Other than that, I think we always trust the ACPI data.

Seems to me you answered your question. It should be possible
to do the same if you replace (ACPI, BIOS) with (ACPI, FDT).
Plus, hopefully there should be no reason to specify data in FDT
that is already provided through ACPI. If it is specified anyway,
its handling is a matter of policy.

Guenter

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