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authorLinus Torvalds <torvalds@linux-foundation.org>2021-05-06 09:56:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-06 09:56:26 -0700
commit164e64adc246dd4239ab644dff86241d17cef218 (patch)
tree9f5c402a7f2b36f9e012d3c79cb993422a099494 /Documentation
parent2423e142b37e2fcce61ea6d3c2f103384ae05f92 (diff)
parent3da53c754502acf74d4d9ba8ac23fc356e6c3d0f (diff)
Merge tag 'acpi-5.13-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull ACPI fixes from Rafael Wysocki: "These revert one recent commit that turned out to be problematic, address two issues in the ACPI "custom method" interface and update GPIO properties documentation. Specifics: - Revent recent commit related to the handling of ACPI power resources during initialization, because it turned out to cause problems to occur on some systems (Rafael Wysocki). - Fix potential use-after-free and potential memory leak in the ACPI "custom method" debugfs interface (Mark Langsdorf). - Update ACPI GPIO properties documentation to cover assumptions regarding GPIO polarity (Andy Shevchenko)" * tag 'acpi-5.13-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: Revert "ACPI: scan: Turn off unused power resources during initialization" ACPI: custom_method: fix a possible memory leak ACPI: custom_method: fix potential use-after-free issue Documentation: firmware-guide: gpio-properties: Add note to SPI CS case
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/firmware-guide/acpi/gpio-properties.rst6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/firmware-guide/acpi/gpio-properties.rst b/Documentation/firmware-guide/acpi/gpio-properties.rst
index 4e264c16ddff..df4b711053ee 100644
--- a/Documentation/firmware-guide/acpi/gpio-properties.rst
+++ b/Documentation/firmware-guide/acpi/gpio-properties.rst
@@ -99,6 +99,12 @@ native::
}
}
+Note, that historically ACPI has no means of the GPIO polarity and thus
+the SPISerialBus() resource defines it on the per-chip basis. In order
+to avoid a chain of negations, the GPIO polarity is considered being
+Active High. Even for the cases when _DSD() is involved (see the example
+above) the GPIO CS polarity must be defined Active High to avoid ambiguity.
+
Other supported properties
==========================