[patch 32/47] rtc: fix reported IRQ rate for when HPET is enabled

From: Greg KH
Date: Tue Jul 22 2008 - 19:29:15 EST

2.6.25-stable review patch. If anyone has any objections, please let us

From: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>

commit 61ca9daa2ca3022dc9cb22bd98e69c1b61e412ad upstream

The IRQ rate reported back by the RTC is incorrect when HPET is enabled.

Newer hardware that has HPET to emulate the legacy RTC device gets this value
wrong since after it sets the rate, it returns before setting the variable
used to report the IRQ rate back to users of the device -- so the set rate and
the reported rate get out of sync.

Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: David Brownell <david-b@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

drivers/char/rtc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/char/rtc.c
+++ b/drivers/char/rtc.c
@@ -677,12 +677,13 @@ static int rtc_do_ioctl(unsigned int cmd
if (arg != (1<<tmp))
return -EINVAL;

+ rtc_freq = arg;
spin_lock_irqsave(&rtc_lock, flags);
if (hpet_set_periodic_freq(arg)) {
spin_unlock_irqrestore(&rtc_lock, flags);
return 0;
- rtc_freq = arg;

val |= (16 - tmp);

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