linux-kernel - [PATCH 4/5] i386: i8253 clockevent shutdown and unused using pit

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Date:	Tue, 8 May 2007 02:46:28 -0700
From:	Chris Wright <chrisw@...s-sol.org>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Chris Wright <chrisw@...s-sol.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	john stultz <johnstul@...ibm.com>, Ingo Molnar <mingo@...e.hu>,
	Arjan van de Ven <arjan@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>, Andi Kleen <ak@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Joachim Deguara <joachim.deguara@....com>
Subject: [PATCH 4/5] i386: i8253 clockevent shutdown and unused using pit

Disable by programming pit directly when performing CLOCK_EVT_MODE_UNUSED
or CLOCK_EVT_MODE_SHUTDOWN transitions.  (A variant) tested successfully
by Joachim Deguara on a Geode that exhibited BZ 8027 behaviour (with
bad bogomips).

Signed-off-by: Chris Wright <chrisw@...s-sol.org>
Cc: Joachim Deguara <joachim.deguara@....com>
---
 arch/i386/kernel/i8253.c |   25 ++++---------------------
 1 file changed, 4 insertions(+), 21 deletions(-)

--- tglx.orig/arch/i386/kernel/i8253.c
+++ tglx/arch/i386/kernel/i8253.c
@@ -29,24 +29,6 @@ EXPORT_SYMBOL(i8253_lock);
  */
 struct clock_event_device *global_clock_event;
 
-/* Status of the PIT interrupt */
-static int pit_irq_disabled;
-
-/*
- * Control pit interrupt enable / disable
- */
-static void pit_control_irq(int disable)
-{
-	if (pit_irq_disabled == disable)
-		return;
-
-	pit_irq_disabled = disable;
-	if (disable)
-		disable_irq(0);
-	else
-		enable_irq(0);
-}
-
 /*
  * Initialize the PIT timer.
  *
@@ -65,17 +47,18 @@ static void init_pit_timer(enum clock_ev
 		outb_p(0x34, PIT_MODE);
 		outb_p(LATCH & 0xff , PIT_CH0);	/* LSB */
 		outb(LATCH >> 8 , PIT_CH0);	/* MSB */
-		pit_control_irq(0);
 		break;
 
 	case CLOCK_EVT_MODE_SHUTDOWN:
 	case CLOCK_EVT_MODE_UNUSED:
-		pit_control_irq(1);
+		outb_p(0x30, PIT_MODE);
+		outb_p(0, PIT_CH0);	/* LSB */
+		outb_p(0, PIT_CH0);	/* MSB */
 		break;
+
 	case CLOCK_EVT_MODE_ONESHOT:
 		/* One shot setup */
 		outb_p(0x38, PIT_MODE);
-		pit_control_irq(0);
 		break;
 
 	case CLOCK_EVT_MODE_RESUME:
-
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