From: Ingo Molnar <mingo@elte.hu>
To: Len Brown <lenb@kernel.org>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-acpi@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH] ACPI/hpet: prevent boot hang when hpet=force used on ICH-4M
Date: Fri, 24 Apr 2009 08:37:34 +0200 [thread overview]
Message-ID: <20090424063734.GA21739@elte.hu> (raw)
In-Reply-To: <alpine.LFD.2.00.0904231917030.15843@localhost.localdomain>
* Len Brown <lenb@kernel.org> wrote:
> From: Len Brown <len.brown@intel.com>
>
> Linux tells ICH4 users that they can (manually) invoke
> "hpet=force" to enable the undocumented ICH-4M HPET.
> The HPET becomes available for both clocksource and clockevents.
>
> But as of ff69f2bba67bd45514923aaedbf40fe351787c59
> (acpi: fix of pmtimer overflow that make Cx states time incorrect)
> the HPET may be used via clocksource for idle accounting, and
> hpet=force on an ICH4 box hangs boot.
>
> It turns out that touching the MMIO HPET withing
> the ARB_DIS part of C3 will hang the hardware.
>
> The fix is to simply move the timer access outside
> the ARB_DIS region. This is a no-op on modern hardware
> because ARB_DIS is no longer used.
>
> http://bugzilla.kernel.org/show_bug.cgi?id=13087
Nice fix! This moots the other half-quirk patch you wrote for hpet,
right?
Ingo
next prev parent reply other threads:[~2009-04-24 6:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-23 2:27 [PATCH] x86/hpet: prevent boot hang when hpet=force used on old ICH Len Brown
2009-04-23 6:09 ` Ingo Molnar
2009-04-23 23:05 ` Len Brown
2009-04-24 23:45 ` Ingo Molnar
2009-04-23 23:18 ` [PATCH] ACPI/hpet: prevent boot hang when hpet=force used on ICH-4M Len Brown
2009-04-23 23:18 ` Pallipadi, Venkatesh
2009-04-23 23:19 ` [PATCH] HPET: stop soliciting hpet=force users on ICH4M Len Brown
2009-04-23 23:19 ` Pallipadi, Venkatesh
2009-04-24 6:43 ` Ingo Molnar
2009-04-24 6:37 ` Ingo Molnar [this message]
2009-04-24 14:49 ` [PATCH] ACPI/hpet: prevent boot hang when hpet=force used on ICH-4M Len Brown
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