[PATCH v1] ALSA: hda/tas2781: Prevent throwing away custom calibration addresses

[Antheas Kapenekakis <lkml@antheas.dev>]

The V2 UEFI spec for per-device calibration data in TAS allows for
manufacturers to specify up to five custom calibration register
addresses and values to optimize per-device in factory.

A basic description of the spec is found in a comment in function
tas2781_apply_calib(). However, currently, for the condition of
p->dspbin_typ != TASDEV_BASIC, if custom calibration addresses have been
provided by the manufacturer, they are ignored and the ones listed in
firmware are used.

In case the manufacturer chose to change different registers other than
the default ones (r0, invr0, r0_low, pow, tlimit), this causes the
UEFI calibration data to scratch different registers and cause the
firmware to misbehave. This is true in the Xbox ROG Ally X, for one of
the firmwares, where it pops and has audio dropouts after the
calibration data is applied.

Therefore, add a new bool to indicate that UEFI supplied custom
calibration addresses, and if so, use them regardless of dspbin_typ.

Link: https://lore.kernel.org/all/CAGwozwFQKoQgo_Q=qdr-FTD+uoVWA8AtHyDmKwTOV4ZU6+F3SQ@mail.gmail.com/
Reported-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Closes: https://lore.kernel.org/all/0ba100d0-9b6f-4a3b-bffa-61abe1b46cd5@linux.dev/
Co-developed-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Signed-off-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>

---
@Matt: can you kindly verify this patch works for you?

Then verify your sign-off for the coby tag. If you would rather a
different acknowledgment tag (e.g., tested-by or suggested-by), lmk

Thanks.
Antheas
---
 sound/hda/codecs/side-codecs/tas2781_hda.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sound/hda/codecs/side-codecs/tas2781_hda.c b/sound/hda/codecs/side-codecs/tas2781_hda.c
index 96e6d82dc69e..6efdf0a3442b 100644
--- a/sound/hda/codecs/side-codecs/tas2781_hda.c
+++ b/sound/hda/codecs/side-codecs/tas2781_hda.c
@@ -64,6 +64,7 @@ static void tas2781_apply_calib(struct tasdevice_priv *p)
 		TASDEVICE_REG(0, 0x18, 0x7c),
 	};
 	unsigned int crc, oft, node_num;
+	bool custom_addr = false;
 	unsigned char *buf;
 	int i, j, k, l;
 
@@ -104,6 +105,7 @@ static void tas2781_apply_calib(struct tasdevice_priv *p)
 		for (j = 0, k = 0; j < node_num; j++) {
 			oft = j * 6 + 3;
 			if (tmp_val[oft] == TASDEV_UEFI_CALI_REG_ADDR_FLG) {
+				custom_addr = true;
 				for (i = 0; i < TASDEV_CALIB_N; i++) {
 					buf = &data[(oft + i + 1) * 4];
 					cali_reg[i] = TASDEVICE_REG(buf[1],
@@ -151,7 +153,7 @@ static void tas2781_apply_calib(struct tasdevice_priv *p)
 		}
 	}
 
-	if (p->dspbin_typ == TASDEV_BASIC) {
+	if (custom_addr || p->dspbin_typ == TASDEV_BASIC) {
 		r->r0_reg = cali_reg[0];
 		r->invr0_reg = cali_reg[1];
 		r->r0_low_reg = cali_reg[2];

base-commit: 9ace4753a5202b02191d54e9fdf7f9e3d02b85eb
-- 
2.52.0