linux-kernel - [PATCH] reboot: perform warm/cold reset correctly for CF9 type

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Date:	Wed, 21 Aug 2013 09:52:29 +0800
From:	Li Fei <fei.li@...el.com>
To:	hpa@...or.com, mingo@...hat.com, tglx@...utronix.de
Cc:	chuansheng.liu@...el.com, x86@...nel.org,
	akpm@...ux-foundation.org, holt@....com,
	rmk+kernel@....linux.org.uk, linux-kernel@...r.kernel.org
Subject: [PATCH] reboot: perform warm/cold reset correctly for CF9 type

In current implementation for reboot type CF9 and CF9_COND,
warm and cold reset are not differentiated, and both are
performed by writing 0x06 to port 0xCF9 as warm reset. It's not
correct.

This commit will differentiate warm and cold reset, and perform
them correctly as below:
For warm reset, write 0x06 to port 0xCF9;
For cold reset, write 0x0E to port 0xCF9.

From: Liu Chuansheng <chuansheng.liu@...el.com>
Signed-off-by: Li Fei <fei.li@...el.com>
---
 arch/x86/kernel/reboot.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 563ed91..6e06299 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -511,10 +511,15 @@ static void native_machine_emergency_restart(void)
 
 		case BOOT_CF9_COND:
 			if (port_cf9_safe) {
-				u8 cf9 = inb(0xcf9) & ~6;
+				u8 cf9 = inb(0xcf9) &
+						~(reboot_mode == REBOOT_WARM ?
+						0x06 : 0x0E);
 				outb(cf9|2, 0xcf9); /* Request hard reset */
 				udelay(50);
-				outb(cf9|6, 0xcf9); /* Actually do the reset */
+				/* Actually do the reset */
+				outb(cf9|(reboot_mode == REBOOT_WARM ?
+					0x06 : 0x0E),
+					0xcf9);
 				udelay(50);
 			}
 			reboot_type = BOOT_KBD;
-- 
1.7.4.1



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