alder_lake_bios/Intel/AlderLake/Features/Audio/NhltFeaturePkg

Overview

• Feature Name: Nhlt platform driver - Non HD Audio Link Table. This is an ACPI table containing non-HD Audio endpoints and links configuration.
• PI Phase(s) Supported: DXE
• SMM Required: No

Purpose

This feature enable flows for creating and installing Nhlt (Non HD Audio Link Table) configuration for integrated DSP on Intel platforms.

Currently supported use cases:

• Driver strength selection
• Add selected group of endpoints to Nhlt configuration
• Install Nhlt configurations under XSDT Acpi table

High-Level Theory of Operation

Feature consists of a single driver(NhltInstallTable.inf) which is responsible for installing the Nhlt table under XSDT Acpi table. Based on selected options in EFI variable NHLT_ENDPOINTS_TABLE_CONFIGURATION_VARIABLE corresponding group of endpoints is added to Nhlt configuration. After publication of Nhlt configuration driver(NhltInstallTable.inf), looks for installed configuration in XSDT and validates NHLT configruation.

The NhltInstallTable.inf entry point has to be executed before drivers start binding to the hardware. It is board responsibility to place them in flash in a way that meets this requirement.

Modules

• NhltInstallTable.inf

Configuration

Set gNhltFeaturePkgTokenSpaceGuid.PcdNhltFeatureEnable to false to disable all of the Nhlt modules.

Data flows

Board can pass endpoints configuration to the feature using below EFI variable:

Type	Variable name	Variable GUID
NHLT_ENDPOINTS_TABLE_CONFIGURATION_VARIABLE	NhltEndpointsTableConfigurationVariable	A1D89A3A-4A90-429D-43651F64C3A29614

Board can publish endpoints configuration under one of selected guids below in FV. For enabling/disabling specific configuration board should use NhltEndpointsTableConfigurationVariable and enable/disable appropriate number of configuration in NhltConfigurationEnabled array.

Number of configuration	Configuration binary GUID in FV	Default
0	06ADC9B7-837F-47DF-AC0C-A0EE18BFAD67	Enabled
1	54067565-B069-4260-87AC-416AC8159BD5	Disabled
2	729D003A-0125-4489-B2EC-00415C88EFEB	Disabled
3	40801B42-4B8E-4CFC-90F6-8AAAEA82607C	Disabled
4	5F845818-7D38-4EBF-B410-922B8CE825BB	Disabled
5	27BDBE6F-4C7A-48AA-9289-4C5A2ECA28D7	Disabled
6	F1722F56-F045-4CA6-A84F-6A7CA1A14C8C	Disabled
7	0046A325-B87B-4DD3-8A6F-6ABACC9EFD5A	Disabled
8	4D77B5D2-A3B5-4ABE-BF70-F982B2BB2EED	Disabled
9	9E83AE47-0DB1-4BE0-9478-6E86366D5EA4	Disabled
10	CE49BFC7-EEBF-49B9-B5D0-94A771659B00	Disabled
11	7DA9FE6F-0AA9-443C-9CA8-231EBBC92B4B	Disabled
12	DCE94204-618E-4289-B97A-00CF43FDB29A	Disabled
13	01A63902-0EFA-4AFF-83A0-FC1B909ECDDF	Disabled
14	C7227C60-F6FC-48EE-A148-19A4D065F47D	Disabled
15	4EC0C41E-40D5-4760-AB08-11EFC717BAAE	Disabled

If NhltEndpointsTableConfigurationVariable EFI variable was not installed NhltInstallTable driver load defaults in LoadNhltConfigurationDefaults () from PCD (NhltConfigurationsEnabledDefaults). User can override Nhlt configuration settings using NhltConfigurationsEnabledDefaults.

Build flows

Nothing special tools are required to build this feature.

Feature Enabling Checklist

1. Add NhltFeature.dsc entry and path to your build file and check if all required packages/libraries exists for this package.
2. Add PostMemory.fdf entry and path to your flash map file.
3. Publish up to 16 endpoints configuration in your flash map and assign correct guids
4. Install NhltEndpointsTableConfigurationVariable and select proper configuration.
5. Set gNhltFeaturePkgTokenSpaceGuid.PcdNhltFeatureEnable to true.