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Subject[PATCH v1 2/9] docs: firmware-guide: ACPI: Clarify ACPI bus concepts
Date
Some devices implement ACPI driver as a way to manage devices
enumerated by the ACPI. This might be confusing as a preferred way to
implement a driver for devices not connected to any bus is a platform
driver, as stated in the documentation. Clarify relationships between
ACPI device, platform device and ACPI entries.

Suggested-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>
---
Documentation/firmware-guide/acpi/enumeration.rst | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/Documentation/firmware-guide/acpi/enumeration.rst b/Documentation/firmware-guide/acpi/enumeration.rst
index 56d9913a3370..f56cc79a9e83 100644
--- a/Documentation/firmware-guide/acpi/enumeration.rst
+++ b/Documentation/firmware-guide/acpi/enumeration.rst
@@ -64,6 +64,19 @@ If the driver needs to perform more complex initialization like getting and
configuring GPIOs it can get its ACPI handle and extract this information
from ACPI tables.

+ACPI bus
+====================
+
+Historically some devices not connected to any bus were represented as ACPI
+devices, and had to implement ACPI driver. This is not a preferred way for new
+drivers. As explained above devices not connected to any bus should implement
+platform driver. ACPI device would be created during enumeration nonetheless,
+and would be accessible through ACPI_COMPANION() macro, and the ACPI handle would
+be accessible through ACPI_HANDLE() macro. ACPI device is meant to describe
+information related to ACPI entry e.g. handle of the ACPI entry. Think -
+ACPI device interfaces with the FW, and the platform device with the rest of
+the system.
+
DMA support
===========

--
2.41.0
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