| Message ID | alpine.LFD.2.00.0905152233180.4571@localhost.localdomain (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
>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@kernel.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@vger.kernel.org; linux-acpi@vger.kernel.org; Moore, Robert >Subject: [PATCH] ACPI: resume: re-enable SCI-enable workaround > >From: Lin Ming <ming.m.lin@intel.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@intel.com> >Signed-off-by: Len Brown <len.brown@intel.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 > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> >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. "We" here means Linux, and thus the description is accurate. The fact is that in 2.6.29 Linux had ACPI_PM1_CONTROL_PRESERVED_BITS 0x0200 and when "we" updated it to 0x201 via the ACPICA update, the workaround in the Linux resume code became a NOP. -Len -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
ACPICA did not change the SCI_EN value. The #define associated with the control register has always been 0x0201 in ACPICA. A linux patch changes the value from 0x0201 to 0x0200, and represents a divergence of linux from ACPICA. What ACPICA did was to rename the #define, that is what broke the linux patch. - #define ACPI_PM1_CONTROL_PRESERVED_BITS 0x0201 /* Bit 9, Bit 0 (SCI_EN) */ + #define ACPI_PM1_CONTROL_IGNORED_BITS 0x0201 /* Bits 9, 0(SCI_EN) */ + #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) >-----Original Message----- >From: Len Brown [mailto:lenb@kernel.org] >Sent: Friday, May 15, 2009 10:50 PM >To: Moore, Robert >Cc: Bob Copeland; Rafael J. Wysocki; Lin, Ming M; Bjorn Helgaas; Zhao, >Yakui; linux-kernel@vger.kernel.org; linux-acpi@vger.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. > >"We" here means Linux, and thus the description is accurate. > >The fact is that in 2.6.29 Linux had >ACPI_PM1_CONTROL_PRESERVED_BITS 0x0200 >and when "we" updated it to 0x201 via the ACPICA update, >the workaround in the Linux resume code became a NOP. > >-Len -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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)