Re: PIC probing code from e179f6914152 failing

[Mario Limonciello]

On 10/23/2023 12:50, Thomas Gleixner wrote:
> On Mon, Oct 23 2023 at 11:17, Mario Limonciello wrote:
> > On 10/23/2023 10:59, Thomas Gleixner wrote:
> > > > IOW NULL pic case has IORESOURCE_DISABLED / IORESOURCE_UNSET
> > >
> > > So the real question is WHY are the DISABLED/UNSET flags not set in the
> > > PIC case?
>
> Do you have an answer for this?

Here's the problematic call path:

acpi_dev_get_irqresource()
->acpi_register_gsi()
->->__acpi_register_gsi() [ Which is acpi_register_gsi_ioapic() ]
->->->mp_map_gsi_to_irq()
->->->->mp_map_pin_to_irq()
->->->->->mp_check_pin_attr()

In the legacy PIC programmed case this function can overwrite level and 
active when acpi_register_gsi() is called.

Without the change I made in the NULL PIC case it can't.
So the resources get disabled by acpi_dev_get_irqresource().

>   
> > > > NULL case:
> > > > handler:  handle_edge_irq
> > > > dstate:   0x3740c208
> > > >                IRQ_TYPE_LEVEL_LOW
> > > >
> > > > PIC case:
> > > > handler:  handle_fasteoi_irq
> > > > dstate:   0x3740e208
> > > >                IRQ_TYPE_LEVEL_LOW
> > > >                IRQD_LEVEL
> > > >
> > > > I guess something related to the callpath for mp_register_handler().
> > >
> > > Guessing is not helpful.
> > >
> > > There is a difference in how the allocation info is set up when legacy
> > > PIC is enabled, but that does not explain the above resource flag
> > > difference.
> >
> > I did a pile of printks and that's how I realized it's because of the
> > missing call to mp_register_handler() which is dependent upon what
> > appeared to me to be a superfluous number of legacy IRQs check (patch 1
> > in my solution).
>
> What exactly is superfluous about these legacy checks?
>
> Thanks,
>
>          tglx

acpi_dev_get_irqresource() tries to set up to match what's in _CRS.
If acpi_register_gsi() fails, the resource can't get setup.