Merge tag 'acpica-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull ACPICA updates from Rafael Wysocki:
 "Additional ACPICA material for v4.2-rc1

  This will update the ACPICA code in the kernel to upstream revision
  20150619 (a bug-fix release mostly including stable-candidate fixes)
  and restore an earlier ACPICA commit that had to be reverted due to a
  regression introduced by it (the regression is addressed by
  blacklisting the only known system affected by it to date).

  The only new feature added by this update is the support for
  overriding objects in the ACPI namespace and a new ACPI table that can
  be used for that called the Override System Definition Table (OSDT).
  That should allow us to "patch" the ACPI namespace built from
  incomplete or incorrect ACPI System Definition tables (DSDT, SSDT)
  during system startup without the need to provide replacements for all
  of those tables in the future.

  Specifics:

   - Fix system resume problems related to 32-bit and 64-bit versions of
     the Firmware ACPI Control Structure (FACS) in the firmare (Lv
     Zheng)

   - Fix double initialization of the FACS (Lv Zheng)

   - Add _CLS object processing code to ACPICA (Suravee Suthikulpanit)

   - Add support for the (currently missing) new GIC version field in
     the Multiple APIC Description Table (MADT) (Hanjun Guo)

   - Add support for overriding objects in the ACPI namespace to ACPICA
     and OSDT support (Lv Zheng, Bob Moore, Zhang Rui)

   - Updates related to the TCPA and TPM2 ACPI tables (Bob Moore)

   - Restore the commit modifying _REV to always return "2" (as required
     by ACPI 6) and add a blacklisting mechanism for systems that may be
     affected by that change (Rafael J Wysocki)

   - Assorted fixes and cleanups (Bob Moore, Lv Zheng, Sascha Wildner)"

* tag 'acpica-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (28 commits)
  Revert 'Revert "ACPICA: Permanently set _REV to the value '2'."'
  ACPI / init: Make it possible to override _REV
  ACPICA: Update version to 20150619
  ACPICA: Comment update, no functional change
  ACPICA: Update TPM2 ACPI table
  ACPICA: Update definitions for the TCPA and TPM2 ACPI tables
  ACPICA: Split C library prototypes to new header
  ACPICA: De-macroize calls to standard C library functions
  ACPI / acpidump: Update acpidump manual
  ACPICA: acpidump: Convert the default behavior to dump from /sys/firmware/acpi/tables
  ACPICA: acpidump: Allow customized tables to be dumped without accessing /dev/mem
  ACPICA: Cleanup output for the ASL Debug object
  ACPICA: Update for acpi_install_table memory types
  ACPICA: Namespace: Change namespace override to avoid node deletion
  ACPICA: Namespace: Add support of OSDT table
  ACPICA: Namespace: Add support to allow overriding objects
  ACPICA: ACPI 6.0: Add values for MADT GIC version field
  ACPICA: Utilities: Add _CLS processing
  ACPICA: Add dragon_fly support to unix file mapping file
  ACPICA: EFI: Add EFI interface definitions to eliminate dependency of GNU EFI
  ...

1 files changed, 20 insertions, 0 deletions

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index f15db002be8e..114cf48085ab 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -80,6 +80,26 @@ config ACPI_PROCFS_POWER
 
 	  Say N to delete power /proc/acpi/ directories that have moved to /sys/
 
+config ACPI_REV_OVERRIDE_POSSIBLE
+	bool "Allow supported ACPI revision to be overriden"
+	depends on X86
+	default y
+	help
+	  The platform firmware on some systems expects Linux to return "5" as
+	  the supported ACPI revision which makes it expose system configuration
+	  information in a special way.
+
+	  For example, based on what ACPI exports as the supported revision,
+	  Dell XPS 13 (2015) configures its audio device to either work in HDA
+	  mode or in I2S mode, where the former is supposed to be used on Linux
+	  until the latter is fully supported (in the kernel as well as in user
+	  space).
+
+	  This option enables a DMI-based quirk for the above Dell machine (so
+	  that HDA audio is exposed by the platform firmware to the kernel) and
+	  makes it possible to force the kernel to return "5" as the supported
+	  ACPI revision via the "acpi_rev_override" command line switch.
+
 config ACPI_EC_DEBUGFS
 	tristate "EC read/write access through /sys/kernel/debug/ec"
 	default n