27 lines
812 B
Plaintext
27 lines
812 B
Plaintext
|
From: Takashi Iwai <tiwai@suse.de>
|
||
|
|
Subject: x86: workaround for mccreary HPET read problem
|
||
|
|
Patch-mainline: not yet
|
||
|
|
References: bnc#433746
|
||
|
|
|
||
|
|
On mccreacy platform, the read of HPET CMP register seems not updated
|
||
|
|
immediately after the write and returns the previous value instead.
|
||
|
|
A workaround is to read the register twice.
|
||
|
|
|
||
|
|
Signed-off-by: Takashi Iwai <tiwai@suse.de>
|
||
|
|
|
||
|
|
---
|
||
|
|
---
|
||
|
|
arch/x86/kernel/hpet.c | 1 +
|
||
|
|
1 file changed, 1 insertion(+)
|
||
|
|
|
||
|
|
--- a/arch/x86/kernel/hpet.c
|
||
|
|
+++ b/arch/x86/kernel/hpet.c
|
||
|
|
@@ -385,6 +385,7 @@ static int hpet_next_event(unsigned long
|
||
|
|
cnt += (u32) delta;
|
||
|
|
hpet_writel(cnt, HPET_Tn_CMP(timer));
|
||
|
|
|
||
|
|
+ hpet_readl(HPET_Tn_CMP(timer)); /* pre-read for bnc#433746 */
|
||
|
|
/*
|
||
|
|
* We need to read back the CMP register on certain HPET
|
||
|
|
* implementations (ATI chipsets) which seem to delay the
|