From: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
To: lkml <linux-kernel@vger.kernel.org>
Subject: [PATCH][i386] HPET setup, duplicate HPET_T0_CMP needed for some platforms
Date: Fri, 4 Feb 2005 15:41:59 -0800 [thread overview]
Message-ID: <20050204154159.A4402@unix-os.sc.intel.com> (raw)
In-Reply-To: <20050204200238.GA5510@ucw.cz>; from vojtech@suse.cz on Fri, Feb 04, 2005 at 09:02:38PM +0100
This patch fixes the issue with HPET on some platforms.
According to Vojtech Pavlik:
The first write after writing TN_SETVAL to the config register sets the
counter value, the second write sets the threshold.
When you only do the first write you never set the threshold and
interrupts won't be generated properly.
Thanks to John Stultz and Andrew Walrond for reporting, root causing
the issue and verifying this fix.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
--- linux-2.6.10/arch/i386/kernel/time_hpet.c.org 2005-02-04 12:04:09.000000000 -0800
+++ linux-2.6.10/arch/i386/kernel/time_hpet.c 2005-02-04 18:01:25.000000000 -0800
@@ -81,6 +81,11 @@ static int hpet_timer_stop_set_go(unsign
cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
HPET_TN_SETVAL | HPET_TN_32BIT;
hpet_writel(cfg, HPET_T0_CFG);
+ /*
+ * Some systems seems to need two writes to HPET_T0_CMP,
+ * to get interrupts working
+ */
+ hpet_writel(tick, HPET_T0_CMP);
hpet_writel(tick, HPET_T0_CMP);
/*
next prev parent reply other threads:[~2005-02-04 23:44 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-03 14:28 i386 HPET code Pallipadi, Venkatesh
2005-02-03 19:30 ` john stultz
2005-02-03 20:02 ` Venkatesh Pallipadi
2005-02-03 21:22 ` Andi Kleen
2005-02-04 17:22 ` Andrew Walrond
2005-02-03 21:30 ` Andi Kleen
2005-02-04 19:28 ` Vojtech Pavlik
2005-02-04 20:02 ` Vojtech Pavlik
2005-02-04 20:03 ` Vojtech Pavlik
2005-02-04 23:41 ` Venkatesh Pallipadi [this message]
2005-02-05 10:55 ` [PATCH][i386] HPET setup, duplicate HPET_T0_CMP needed for some platforms Andrew Walrond
2005-02-06 15:58 ` Giuseppe Bilotta
-- strict thread matches above, loose matches on Subject: below --
2005-02-07 19:47 Pallipadi, Venkatesh
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