Re: [PATCH v3 0/3] Fix CS35L56 amplifier on Intel LPSS SPI with broken ACPI cs-gpios

[Juan Jimenez Carrero]

On 03/09/2026 10:21 am, Richard Fitzgerald wrote:
> HP told us they have a BIOS with the cs-gpios fixed, and they can make
> that available early if you post a support request for it.
>
> Can you test that new BIOS? It would avoid the messy SPI workarounds.

I have affected hardware. I could raise a support request and
test that BIOS, if a second machine doing so is useful:

  HP EliteBook 8 G1i 14 inch, SKU D75TQET#ABE
  BIOS X91 Ver. 01.05.02, 05/03/2026
  Intel Core Ultra 5 238V (Lunar Lake-M)
  SPI controller 8086:a827 (LPSS_CNL_SSP via tgl_spi_info)
  Realtek ALC245, SSID 103c:8d8f
  2x Cirrus Logic CS35L54 Rev B0 OTP4 fw:3.4.4, ACPI HID CSC3554

This is the CS35L54 variant rather than CS35L56, so it may be a useful
extra data point either way. The DSDT defect is identical:

  Scope (_SB.PC00.SPI0)
  {
      Name (_DSD, Package (0x02)
      {
          ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
          Package (0x01)
          {
              Package (0x02) { "cs-gpios", Package (0x01) { Zero } }
          }
      })
  }

while GSPK._CRS declares SpiSerialBusV2 with DeviceSelection 0x0000 and
0x0001, plus a GpioIo for the CS1 line.

One difference from the cover letter's description: on this machine
neither amplifier is instantiated on a stock kernel, not only the
second. spi_add_device() rejects CS1 and serial-multi-instantiate then
unwinds the whole set:

  pxa2xx-spi pxa2xx-spi.3: cs1 >= max 1
  spi_master spi1: error -EINVAL: failed to add SPI device CSC3554:00 from ACPI
  Serial bus multi instantiate pseudo device driver CSC3554:00: probe with
    driver Serial bus multi instantiate pseudo device driver failed with error -22

For reference, the LPSS capability register on this board reads
caps[0xfc] = 0x220, so CS_EN (bits 12:9) is 0x1 and ffz() yields
num_chipselect = 1, while ACPI describes two chip selects. The TYPE
field of the same register reads 2 (LPSS_DEV_SPI), so the read itself
is valid. (Obtained with a dev_info() added to spi-pxa2xx.c; the
register is not reachable from userspace with CONFIG_IO_STRICT_DEVMEM)

I have run the earlier two-patch version from your gist
(serial-multi-instantiate + spi-pxa2xx), built out-of-tree as a DKMS
module against 7.1.9. With those applied both amplifiers probe, load
firmware and calibration, and bind to the codec. Internal speakers work
across a cold boot:

  serial-multi-instantiate CSC3554:00: Increasing num_chipselect from 1 to 2 for CS1
  serial-multi-instantiate CSC3554:00: Got CS GPIO for amp CS1
  cs35l56-hda spi1-CSC3554:00-cs35l54-hda.0: DSP system name: '103C8D8F', amp name: 'AMP1'
  cs35l56-hda spi1-CSC3554:00-cs35l54-hda.1: DSP system name: '103C8D8F', amp name: 'AMP2'
  snd_hda_codec_alc269 ehdaudio0D0: bound spi1-CSC3554:00-cs35l54-hda.0
  snd_hda_codec_alc269 ehdaudio0D0: bound spi1-CSC3554:00-cs35l54-hda.1
  cs35l56-hda spi1-CSC3554:00-cs35l54-hda.0: Calibration applied
  cs35l56-hda spi1-CSC3554:00-cs35l54-hda.1: Calibration applied

I have not tested v3, so I am deliberately not offering a Tested-by for
it. I can test v3, the new BIOS or both on this machine (whichever is
more useful).

Juan Jimenez Carrero