linux-kernel - [PATCH] ACPI: Do not modify SCI

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Message-Id: <200812291919.07663.rjw@sisk.pl>
Date:	Mon, 29 Dec 2008 19:19:07 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Len Brown <lenb@...nel.org>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: [PATCH] ACPI: Do not modify SCI_EN directly

From: Rafael J. Wysocki <rjw@...k.pl>

According to the ACPI specification the SCI_EN flag is controlled by
the hardware, which sets this flag to inform the kernel that ACPI is
enabled.  For this reason, we shouldn't try to modify SCI_EN
directly.  Also, we don't need to do it in irqrouter_resume(), since
lower-level resume code takes care of enabling ACPI in case it hasn't
been enabled by the BIOS before passing control to the kernel (which
by the way is against the ACPI specification).

Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
 drivers/acpi/pci_link.c |    4 ----
 1 file changed, 4 deletions(-)

Index: linux-2.6/drivers/acpi/pci_link.c
===================================================================
--- linux-2.6.orig/drivers/acpi/pci_link.c
+++ linux-2.6/drivers/acpi/pci_link.c
@@ -793,10 +793,6 @@ static int irqrouter_resume(struct sys_d
 	struct list_head *node = NULL;
 	struct acpi_pci_link *link = NULL;
 
-
-	/* Make sure SCI is enabled again (Apple firmware bug?) */
-	acpi_set_register(ACPI_BITREG_SCI_ENABLE, 1);
-
 	list_for_each(node, &acpi_link.entries) {
 		link = list_entry(node, struct acpi_pci_link, node);
 		if (!link) {
.