Documentation/sound/codecs/cs35l56.rst

Source file repositories/reference/linux-study-clean/Documentation/sound/codecs/cs35l56.rst

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Documentation/sound/codecs/cs35l56.rst
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Support Tooling And Documentation
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Support Tooling And Documentation: documentation
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.. SPDX-License-Identifier: GPL-2.0-only

========================================================================
Audio drivers for Cirrus Logic CS35L54/56/57/63 Boosted Smart Amplifiers
========================================================================
:Copyright: 2025 Cirrus Logic, Inc. and
                 Cirrus Logic International Semiconductor Ltd.

Contact: patches@opensource.cirrus.com

Summary
=======

The high-level summary of this document is:

**If you have a laptop that uses CS35L54/56/57/63 amplifiers but audio is not
working, DO NOT ATTEMPT TO USE FIRMWARE AND SETTINGS FROM ANOTHER LAPTOP,
EVEN IF THAT LAPTOP SEEMS SIMILAR.**

The CS35L54/56/57/63 amplifiers must be correctly configured for the power
supply voltage, speaker impedance, maximum speaker voltage/current, and
other external hardware connections.

The amplifiers feature advanced boost technology that increases the voltage
used to drive the speakers, while proprietary speaker protection algorithms
allow these boosted amplifiers to push the limits of the speakers without
causing damage. These **must** be configured correctly.

Supported Cirrus Logic amplifiers
---------------------------------

The cs35l56 drivers support:

* CS35L54
* CS35L56
* CS35L57
* CS35L63

There are two drivers in the kernel

*For systems using SoundWire*: sound/soc/codecs/cs35l56.c and associated files

*For systems using HDA*: sound/hda/codecs/side-codecs/cs35l56_hda.c

Firmware
========

The amplifier is controlled and managed by firmware running on the internal
DSP. Firmware files are essential to enable the full capabilities of the
amplifier.

Firmware is distributed in the linux-firmware repository:
https://gitlab.com/kernel-firmware/linux-firmware.git

On most SoundWire systems the amplifier has a default minimum capability to
produce audio. However this will be

* at low volume, to protect the speakers, since the speaker specifications
  and power supply voltages are unknown.
* a mono mix of left and right channels.

On some SoundWire systems that have both CS42L43 and CS35L56/57 the CS35L56/57
receive their audio from the CS42L43 instead of directly from the host
SoundWire interface. These systems can be identified by the CS42L43 showing
in dmesg as a SoundWire device, but the CS35L56/57 as SPI. On these systems
the firmware is *mandatory* to enable receiving the audio from the CS42L43.

On HDA systems the firmware is *mandatory* to enable HDA bridge mode. There
will not be any audio from the amplifiers without firmware.

Annotation

Implementation Notes