1 files changed, 7 insertions, 0 deletions

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 801497a16e0e..73deaffadd03 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -278,6 +278,13 @@ static int hpet_legacy_next_event(unsigned long delta,
         cnt += (u32) delta;
         hpet_writel(cnt, HPET_T0_CMP);
 
+        /*
+         * We need to read back the CMP register to make sure that
+         * what we wrote hit the chip before we compare it to the
+         * counter.
+         */
+        WARN_ON((u32)hpet_readl(HPET_T0_CMP) != cnt);
+
         return (s32)((u32)hpet_readl(HPET_COUNTER) - cnt) >= 0 ? -ETIME : 0;
 }