From: Len Brown Date: Thu, 23 Apr 2009 22:59:43 +0000 (-0400) Subject: ACPI/hpet: prevent boot hang when hpet=force used on ICH-4M X-Git-Tag: v2.6.30-rc4~50^2~4^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f461ddea0af8b98e2b7940eba9c693b0ee44d64a;p=pandora-kernel.git ACPI/hpet: prevent boot hang when hpet=force used on ICH-4M 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 Acked-by: Venkatesh Pallipadi Signed-off-by: Len Brown --- Reading git-diff-tree failed