Re: i8042_init: PS/2 mouse not detected with ACPIPnP/PnPBIOS

["Rafael J. Wysocki" <rafael@kernel.org>]

On Sun, Oct 11, 2020 at 1:08 AM Paul Menzel <pmenzel@molgen.mpg.de> wrote:
>
> Dear Dmitry, dear Rafael, dear Len,
>
>
> Am 08.10.20 um 00:16 schrieb Dmitry Torokhov:
>
> > On Wed, Oct 07, 2020 at 11:18:41PM +0200, Paul Menzel wrote:
>
> >> On the Asus F2A85-M PRO Linux 5.9-rc8 (and previous versions) does not
> >> recognize a plugged in PS/2 mouse using the Plug & Play method. The PS/2
> >> keyboard is detected fine, and using `i8042.nopnp`, the PS/2 mouse also
> >> works.
> >>
> >>> [    1.035915] calling  i8042_init+0x0/0x42d @ 1
> >>> [    1.035947] i8042: PNP: PS/2 Controller [PNP0303:PS2K] at 0x60,0x64 irq 1
> >>> [    1.035948] i8042: PNP: PS/2 appears to have AUX port disabled, if this is incorrect please boot with i8042.nopnp
> >>> [    1.036589] serio: i8042 KBD port at 0x60,0x64 irq 1
> >>> [    1.036621] initcall i8042_init+0x0/0x42d returned 0 after 687 usecs
> >>
> >> But, the DSDT includes the “mouse device”. From
> >>
> >>      acpidump > dump.bin; acpixtract dump.bin; iasl -d *dat; more dsdt.dsl
> >>
> >> we get
> >>
> >>                  Device (PS2M)
> >>                  {
> >>                      Name (_HID, EisaId ("PNP0F03") /* Microsoft PS/2-style Mouse */)  // _HID: Hardware ID
> >>                      Name (_CID, EisaId ("PNP0F13") /* PS/2 Mouse */) // _CID: Compatible ID
> >>                      Method (_STA, 0, NotSerialized)  // _STA: Status
> >>                      {
> >>                          If ((IOST & 0x4000))
> >>                          {
> >>                              Return (0x0F)
> >>                          }
> >>                          Else
> >>                          {
> >>                              Return (Zero)
> >>                          }
> >>                      }
> >>
> >> and the identifiers PNP0F03 and PNP0F13 are both listed in the array
> >> `pnp_aux_devids[]`. But adding print statements to `i8042_pnp_aux_probe()`,
> >> I do not see them, so the function does not seem to be called.
> >
> > My guess is that _STA returns 0 indicating that the device is not
> > present. I would try tracking where IOST is being set and figuring out
> > why it does not have mouse bit enabled.
>
> Does the ACPI subsystem allow to track, how ACPI variables(?) like IOST
> are read and set?

My guess would be that IOST is a field in an operation region which
would indicate that it is initialized by the bootstrap part of the
BIOS.