[PATCH RFC 0/1] ASoC: rt1320: LG gram 16Z95U speaker works with the BIOS init values

[fixca]

From: JaeHoon Kim <jaehoon1744@xxxxxxxxxxxxx>

Hi Shuming,

Follow-up on the silent RT1320 speaker on the LG gram 16Z95U (SSID
1854:056c), from the "SoundWire audio for LG gram 16Z95U" thread. Thanks
to Mark for applying the two ACP patches, and to Vijendar for confirming
the AUDIO1_TX pin.

The speakers now work, with one change in the RT1320 driver: using the
values from the BIOS SDCA function initialization table of the SmartAmp
function instead of rt1320_vc_blind_write[].

Results on 7.2.15 (version_id=2, dev_id=0x6981):

  rt1320_vc_blind_write[]     stream runs without errors, silent at 0 dB
  BIOS init values (patch)    speakers work, correct L/R, no distortion

The BIOS table has the same structure as rt1320_vc_blind_write[]. The
differences are listed in the patch description. Two of them stand out:

 - The L/R mapping in 0x1000db15-0x1000db23 is swapped compared to the
   driver, and the swapped (BIOS) mapping gives the correct channels on
   this machine.
 - Several registers are written only by the BIOS table (0xc5c2-0xc5d0,
   0xc050-0xc063, 0xc582, 0xc60b, 0xc682, 0xdc20, 0xcd00, 0xcf02,
   0xce1b-0xce44), and 0xc900/0xc901 and 0xd471/0xd479 have different
   values.

The attached patch is a test patch against v7.2.15, not meant for merging:
it changes about 50 registers at once and I do not know which ones are
required. DSP firmware and RAE files are still not loaded on this
machine, so the speaker protection that Windows sets up (R0 calibration,
EnableAdvanceMode) is not active.

Questions:

 1. Which of these registers does this design actually need? I can
    test a smaller patch, or narrow it down by removing groups of
    registers if that helps.
 2. Would you prefer the driver to apply the BIOS
    "mipi-sdca-function-initialization-table" in general, or a
    per-machine table like in this patch?
 3. Could Realtek provide DSP firmware / RAE files for this machine
    for linux-firmware?

Thanks,
JaeHoon Kim