HPET: make minimum reprogramming delta useful

The minimum reprogramming delta was hardcoded in HPET ticks,
which is stupid as it does not work with faster running HPETs.
The C1E idle patches made this prominent on AMD/RS690 chipsets,
where the HPET runs with 25MHz. Set it to 5us which seems to be
a reasonable value and fixes the problems on the bug reporters
machines. We have a further sanity check now in the clock events,
which increases the delta when it is not sufficient.

Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Luiz Fernando N. Capitulino <[email protected]>
Tested-by: Dmitry Nezhevenko <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 59fd3b6b13036e1e279e54d0e1e3d3f5ebb55166..2256315416d81e62520a22410ed6596f487996de 100644 (file)
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -210,8 +210,8 @@ static void hpet_legacy_clockevent_register(void)
        /* Calculate the min / max delta */
        hpet_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFFFF,
                                                           &hpet_clockevent);
-       hpet_clockevent.min_delta_ns = clockevent_delta2ns(0x30,
-                                                          &hpet_clockevent);
+       /* 5 usec minimum reprogramming delta. */
+       hpet_clockevent.min_delta_ns = 5000;
 
        /*
         * Start hpet with the boot cpu mask and make it