Arrow Lake-HX (Core Ultra 9 275HX) SOF firmware fails with error 0x97 - CS35L56 amplifiers non-functional #10420

BUG REPORT

Arrow Lake-HX (Core Ultra 9 275HX) SOF firmware fails with signature validation error
0x97 - CS35L56 amplifiers non-functional

Environment
Laptop: Lenovo ThinkBook 16p G6 IAX (Model 21R0)
CPU: Intel Core Ultra 9 275HX (Arrow Lake-HX, Family 6, Model 198)
Audio Codec: Realtek ALC287 (Subsystem 0x17aa3921)
Amplifiers: Cirrus Logic CS35L56 x2 (I2C: CSC3556:00)
Kernel: 6.14.0-36-generic
linux-firmware: 20240318.git3b128b60-0ubuntu2.21
BIOS: Lenovo (up to date via fwupd)

Problem Description
The SOF (Sound Open Firmware) driver fails to load on Arrow Lake-HX laptops with
cryptographic signature validation error 0x97. This prevents the CS35L56 smart amplifiers from
functioning, resulting in either no audio or severely degraded audio quality. You'll find /tmp/alsa-info.txt attached.

alsa-info.txt

Error Log
[
4.849077] sof-audio-pci-intel-mtl 0000:80:1f.3: Firmware file: intel/sof-
ipc4/arl-s/sof-arl-s.ri
[
7.853974] sof-audio-pci-intel-mtl 0000:80:1f.3: 0xd000000c: module:
ROM_EXT, state: VALIDATE_PUB_KEY, not running
[
7.853982] sof-audio-pci-intel-mtl 0000:80:1f.3: error code: 0x97 (unknown)
[
7.854037] sof-audio-pci-intel-mtl 0000:80:1f.3: error: failed to boot DSP
firmware -110

Root Causes Identified

1. Missing signed firmware: The /lib/firmware/intel/sof-ipc4/arl/intel-
   signed/ directory is empty in current linux-firmware packages. Arrow Lake requires
   signed firmware for DSP validation.
2. Platform misdetection: Driver loads arl-s (Arrow Lake-S desktop) firmware instead of
   proper mobile platform firmware.
3. Codec confusion: HDA codec reports as "Intel Meteor Lake HDMI" (vendor 0x8086281d)
   despite Arrow Lake-HX CPU, suggesting BIOS/firmware platform identification issues.
   Impact
   • No working audio path to CS35L56 amplifiers - These require SOF topology for I2S/ASP
   routing• Fallback HDA driver produces tinny sound - Uses analog codec path instead of digital
   amplifier path
   • Affects all Arrow Lake-HX laptops with similar audio configurations

Attempted Workarounds

1. Symlink MTL firmware to ARL path
   ✗ Error 0x97 persists (signature mismatch)
2. Use unsigned ARL firmware
   ✗ Error 0x97 (DSP requires signed firmware)
3. Blacklist SOF, use legacy HDA
   ✓ Partial - audio works but quality poor
4. Kernel parameter snd_sof.tplg_path=
   ✗ Ignored by driver
5. Update BIOS via fwupd
   ✗ No updates available

Required Fixes
Short-term (Critical):

1. Release intel-signed firmware for Arrow Lake to linux-firmware repository
   • Path: intel/sof-ipc4/arl/intel-signed/sof-arl.ri.zst
   • Or clarify if ARL-HX should use MTL signed firmware

Medium-term:
2. Fix platform detection - Distinguish between arl-s (desktop) and arl-h/arl-hx
(mobile)
3. Add topology file for Lenovo ThinkBook + CS35L56 configuration
• Device: sof-arl-cs42l43-l0-cs35l56-l23.tplg exists but isn't loaded

Long-term:
4. Document Arrow Lake-HX audio requirements for OEMs and distros

Additional Information
• Full ALSA diagnostic attached: alsa-info.txt
• CS35L56 amplifiers ARE detected: cs35l56-hda i2c-CSC3556:00 shows in dmesg
• ACPI DMI: sys_vendor: LENOVO, product_name: 21R0

Questions for Intel SOF Team

1. Is Arrow Lake-HX supposed to use signed firmware? (error 0x97 suggests yes)
2. Should ARL-HX use arl, arl-h, or arl-s firmware directory?
3. Is intel-signed ARL firmware blocked by NDA or coming in future release?

Thank you for you help,
kind regards :)