linux-kernel - RE: [PATCH] ACPI: resume: re-enable SCI-enable workaround

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Message-ID: <4911F71203A09E4D9981D27F9D8308582DB914DF@orsmsx503.amr.corp.intel.com>
Date:	Fri, 15 May 2009 20:30:41 -0700
From:	"Moore, Robert" <robert.moore@...el.com>
To:	Len Brown <lenb@...nel.org>, Bob Copeland <me@...copeland.com>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>,
	"Lin, Ming M" <ming.m.lin@...el.com>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	"Zhao, Yakui" <yakui.zhao@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>
Subject: RE: [PATCH] ACPI: resume: re-enable SCI-enable workaround


>The BIOS bug workaround mistakenly got disabled
>when we followed the ACPI specification more closely
>by ignoring OS updates to that bit.

Not exactly. ACPICA has always preserved the SCI_EN bit. Linux apparently has a "linux-only" patch to ACPICA that disables this.

The recent version of ACPICA change the #define enough such that the patch no longer works.


>-----Original Message-----
>From: Len Brown [mailto:lenb@...nel.org]
>Sent: Friday, May 15, 2009 7:34 PM
>To: Bob Copeland
>Cc: Rafael J. Wysocki; Lin, Ming M; Bjorn Helgaas; Zhao, Yakui; linux-
>kernel@...r.kernel.org; linux-acpi@...r.kernel.org; Moore, Robert
>Subject: [PATCH] ACPI: resume: re-enable SCI-enable workaround
>
>From: Lin Ming <ming.m.lin@...el.com>
>
>The BIOS bug workaround mistakenly got disabled
>when we followed the ACPI specification more closely
>by ignoring OS updates to that bit.
>
>(The BIOS is supposed to update SCI_EN, not the OS)
>
>http://bugzilla.kernel.org/show_bug.cgi?id=13289
>
>Signed-off-by: Lin Ming <ming.m.lin@...el.com>
>Signed-off-by: Len Brown <len.brown@...el.com>
>---
>
>as-applied.
>thanks,
>-Len
>
> drivers/acpi/acpica/aclocal.h |    7 ++++++-
> 1 files changed, 6 insertions(+), 1 deletions(-)
>
>diff --git a/drivers/acpi/acpica/aclocal.h b/drivers/acpi/acpica/aclocal.h
>index 772ee5c..2ec394a 100644
>--- a/drivers/acpi/acpica/aclocal.h
>+++ b/drivers/acpi/acpica/aclocal.h
>@@ -787,7 +787,12 @@ struct acpi_bit_register_info {
>
> /* For control registers, both ignored and reserved bits must be preserved
>*/
>
>-#define ACPI_PM1_CONTROL_IGNORED_BITS           0x0201	/* Bits 9,
>0(SCI_EN) */
>+/*
>+ * The ACPI spec says to ignore PM1_CTL.SCI_EN (bit 0)
>+ * but we need to be able to write ACPI_BITREG_SCI_ENABLE directly
>+ * as a BIOS workaround on some machines.
>+ */
>+#define ACPI_PM1_CONTROL_IGNORED_BITS           0x0200	/* Bits 9 */
> #define ACPI_PM1_CONTROL_RESERVED_BITS          0xC1F8	/* Bits 14-15,
>3-8 */
> #define ACPI_PM1_CONTROL_PRESERVED_BITS \
> 	       (ACPI_PM1_CONTROL_IGNORED_BITS |
>ACPI_PM1_CONTROL_RESERVED_BITS)
>--
>1.6.3.1.9.g95405b
>

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