On Thu, 01 Dec 2016 08:19:46 +0100,
Takashi Iwai wrote:
>
> On Thu, 01 Dec 2016 03:29:23 +0100,
> Dmitry Torokhov wrote:
> >
> > Hi Takashi,
> >
> > On Mon, Nov 28, 2016 at 02:56:36PM +0100, Takashi Iwai wrote:
> > > Hi Dmitry,
> > >
> > > I've been testing a small machine with Intel Cherry Trail chipset, and
> > > noticed that the kernel spews errors always like:
> > >
> > > i8042: PNP: No PS/2 controller found. Probing ports directly.
> > > i8042: Can't read CTR while initializing i8042
> > > i8042: probe of i8042 failed with error -5
> > >
> > > Especially the second one ("Can't read CTR...") is annoying since it's
> > > in KERN_ERR level and thus appears even booted with quiet boot
> > > option. Actually this is the only error message appearing at boot, so
> > > I'd love to get rid of it.
> > >
> > > What is the preferred way to reduce this? For example, is a patch
> > > like below OK to simply change the log level and the error code?
> >
> > No, because if controller is actually present this is a hard failure and
> > we should be reporting it, not suppressing it.
> >
> > The issue is that we did not believe PNP data and in this case we should
> > have. Unfortunately in old days there was a lot of crap in PNP/ACPI
> > tables, but it could be better now. We can try, in addition to PNP
> > matching, checking 8042 flag in "Fixed ACPI Description Table Boot
> > Architecture Flags" in FADT and if it also shows there is no 8042 then
> > bail.
>
> That sounds promising. Indeed FACL.dsl shows like:
>
> [000h 0000 4] Signature : "FACP" [Fixed ACPI Description Table (FADT)]
> [004h 0004 4] Table Length : 0000010C
> ....
> Legacy Devices Supported (V2) : 0
> 8042 Present on ports 60/64 (V2) : 0
>
> If a test patch gets ready, let me know, I'll give it a try.
FYI, a hack like below seems working.
Takashi
---
diff --git a/drivers/input/serio/i8042-x86ia64io.h b/drivers/input/serio/i8042-x86ia64io.h
index 073246c7d163..ed6ab702e4b7 100644
--- a/drivers/input/serio/i8042-x86ia64io.h
+++ b/drivers/input/serio/i8042-x86ia64io.h
@@ -9,6 +9,7 @@
#ifdef CONFIG_X86
#include <asm/x86_init.h>
+#include <linux/acpi.h>
#endif
/*
@@ -1055,6 +1056,13 @@ static int __init i8042_pnp_init(void)
#if defined(__ia64__)
return -ENODEV;
#else
+#ifdef CONFIG_ACPI
+ if (acpi_gbl_FADT.header.revision >= 3 &&
+ !(acpi_gbl_FADT.boot_flags & ACPI_FADT_8042)) {
+ pr_info("PNP: No PS/2 controller found and disabled in ACPI\n");
+ return -ENODEV;
+ }
+#endif
pr_info("PNP: No PS/2 controller found. Probing ports directly.\n");
return 0;
#endif
--
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