On Thu, Feb 8, 2018 at 1:55 AM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> On Tuesday, February 6, 2018 6:59:34 AM CET Alex Hung wrote:
>> On Fri, Feb 2, 2018 at 3:25 AM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
>> > On Thursday, February 1, 2018 9:07:59 AM CET Alex Hung wrote:
>> >> On Wed, Jan 31, 2018 at 11:30 PM, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote:
>> >> > On Thu, Feb 1, 2018 at 5:39 AM, Alex Hung <alex.hung@xxxxxxxxxxxxx> wrote:
>> >> >> On Wed, Jan 31, 2018 at 1:20 AM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
>> >> >>> On Wednesday, January 31, 2018 6:52:19 AM CET Alex Hung wrote:
>> >> >>>> In recent Intel hardware the IRQs become non-configurable after BIOS
>> >> >>>> initializes them in PEI phase and _PRS objects are no longer included in
>> >> >>>> ASL.
>> >> >>>>
>> >> >>>> This is the same as "static (non-configurable) devices do not
>> >> >>>> specify a _PRS object" in ACPI spec. As a result, error messages
>> >> >>>> saying "ACPI Exception: AE_NOT_FOUND, Evaluating _PRS" are not
>> >> >>>> needed.
>> >> >>>
>> >> >>> That's questionable at best.
>> >> >>>
>> >> >>> The errors basically indicate that _PRT entries corresponding to these
>> >> >>> IRQs are messed up (because they should contain the value of 0 instead of
>> >> >>> a NamePath in the Source column), so we are now going to paper over bugs
>> >> >>> in ACPI tables as someone in the firmware land cannot be bothered with
>> >> >>> putting correct values into them. :-/
>> >> >>
>> >> >> Rafael,
>> >> >>
>> >> >> Thanks for quick reply and sharing the information
>> >> >>
>> >> >> It seems static (non-configurable) devices on ACPI are discussed in
>> >> >> both _PRS and _PRT as below:
>> >> >>
>> >> >> 6.2.12 _PRS (Possible Resource Settings)
>> >> >> "... Static (non-configurable) devices do not specify a _PRS object... "
>> >> >>
>> >> >> 6.2.13 _PRT (PCI Routing Table)
>> >> >> "In the second model, the PCI interrupts are hardwired to specific
>> >> >> interrupt inputs on the interrupt controller and are not configurable.
>> >> >> In this case, the Source field in _PRT does not reference a device,
>> >> >> but instead contains the value zero, and the Source Index field
>> >> >> contains the global system interrupt to which the PCI interrupt is
>> >> >> hardwired."
>> >> >>
>> >> >> My interpretation is the both are true from ACPI's perspective, and
>> >> >> both should be implemented by system firmware. On this particular
>> >> >> system I am debugging remotely, it does the _PRS part but not _PRT,
>> >> >> and I will follow up with firmware engineers.
>> >> >
>> >> > OK
>> >> >
>> >> >> On the other hand, it may not be unreasonable to remove AE_NOT_FOUND
>> >> >> as defined in 6.2.12 in ACPI spec. I also did a code trace and it
>> >> >> seems that the AE_NOT_FOUND in _PRS cannot be removed by a value of
>> >> >> zero in Source field in _PRT.
>> >> >
>> >> > I'm not sure what you mean here.
>> >> >
>> >> > Do you mean that the code would mishandle 0 in the Source field of _PRT?
>> >>
>> >> I meant the AE_NOT_FOUND messages still pop up when SOURCE = 0.
>> >
>> > OK, so why does the firmware define the link objects in the namespace then?
>> >
>> >> Do you have other comments about this patch or concerns that I can work
>> >> with firmware engineers?
>> >
>> > It looks to me that there are some PCI interrupt link objects in the
>> > namespace without _PRS and which aren't pointed to by any _PRT entries.
>> >
>> > If so, what are they useful for then?
>>
>> The LNKA~LNKD used in Name(PK00) are used when PIC mode is used, ex.
>> _PIC(0).
>
> I see.
>
> OK, in that case I'd just change the log level of the message to "debug",
> and use acpi_handle_debug() for printing it for that matter.
>
Hi Rafael,
Do you mean something like the below change?
if (ACPI_FAILURE(status)) {
- ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PRS"));
+ acpi_handle_debug(link->device->handle, "failed to
evaluate _PRS");
return -ENODEV;
}
If so, I will submit a V2 accordingly.
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