src/patches/suse-2.6.27.31/patches.arch/x86-hpet-pre-read

   1 From: Takashi Iwai <tiwai@suse.de>
   2 Subject: x86: workaround for mccreary HPET read problem
   3 Patch-mainline:
   4 References: bnc#433746
   5
   6 On mccreacy platform, the read of HPET CMP register seems not updated
   7 immediately after the write and returns the previous value instead.
   8 A workaround is to read the register twice.
   9
  10 Signed-off-by: Takashi Iwai <tiwai@suse.de>
  11
  12 ---
  13 --- a/arch/x86/kernel/hpet.c
  14 +++ b/arch/x86/kernel/hpet.c
  15 @@ -278,6 +278,7 @@ static int hpet_legacy_next_event(unsign
  16         cnt += (u32) delta;
  17         hpet_writel(cnt, HPET_T0_CMP);
  18
  19 +       hpet_readl(HPET_T0_CMP); /* pre-read for bnc#433746 */
  20         /*
  21          * We need to read back the CMP register to make sure that
  22          * what we wrote hit the chip before we compare it to the