2010-07-07 11:12:45 +00:00
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From: Takashi Iwai <tiwai@suse.de>
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Subject: x86: workaround for mccreary HPET read problem
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Patch-mainline: not yet
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References: bnc#433746
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On mccreacy platform, the read of HPET CMP register seems not updated
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immediately after the write and returns the previous value instead.
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A workaround is to read the register twice.
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Signed-off-by: Takashi Iwai <tiwai@suse.de>
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---
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---
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arch/x86/kernel/hpet.c | 1 +
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1 file changed, 1 insertion(+)
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--- a/arch/x86/kernel/hpet.c
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+++ b/arch/x86/kernel/hpet.c
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2011-04-19 20:09:59 +00:00
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@@ -386,6 +386,7 @@ static int hpet_next_event(unsigned long
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2010-07-07 11:12:45 +00:00
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cnt += (u32) delta;
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hpet_writel(cnt, HPET_Tn_CMP(timer));
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+ hpet_readl(HPET_Tn_CMP(timer)); /* pre-read for bnc#433746 */
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/*
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* We need to read back the CMP register on certain HPET
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* implementations (ATI chipsets) which seem to delay the
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