ASoC: tas2783-sdw: drop stale regcache on uninitialized re-attach

When the peripheral re-attaches after the SoundWire controller was
power-gated during system suspend (s2idle reaching S0i3 on AMD ACP), the
amplifier has lost all of its register and DSP state. tas_update_status()
handles that by re-running tas_io_init(), which writes the device's
TAS2783_SW_RESET register - a vendor register write that clears the
device's register file and DSP state, not a SoundWire reset, so no
re-enumeration is involved - and re-downloads the firmware. Before doing
any of that, it syncs back a register cache that still holds the
pre-suspend values.

That sync is useless, since the reset immediately wipes whatever it
wrote, and it leaves the cache claiming that the amplifier is already
powered up and unmuted. Subsequent read-modify-write updates - DAPM
amplifier power-up, SDCA PDE transitions at stream start - then see "no
change" and skip the hardware write. Playback runs without a single
error while the speakers stay silent. Unbinding and rebinding the driver
restores audio, since probe starts from a fresh cache.

Drop the cache instead of syncing it when an uninitialized device
attaches, so that later accesses see the real hardware state.

Reordering the sync after tas_io_init() and marking the cache dirty is
not a workable alternative here: tas_regmap has no .writeable_reg, so
the cache accepts every register up to .max_register, including ones for
which tas2783_sdca_mbq_size() returns 0. regmap_sdw_mbq_size() rejects
those with -EINVAL, so the replay fails on the first such register and
takes initialization down with it.

Cached user settings fall back to hardware defaults across such a power
loss, which seems clearly preferable to a silent amplifier - the device
is being reset and its firmware reloaded at this point anyway.

Tested on an ASUS ProArt PX13 HN7306EAC (AMD Strix Halo, ACP7.0, two
TAS2783 amplifiers plus RT721 on SoundWire link 1): the speakers work
after an s2idle resume with ~51 s of S0i3 residency, where previously
they stayed silent despite a complete firmware re-download.

Fixes: 4cc9bd8d7b32 ("ASoc: tas2783A: Add soundwire based codec driver")
Reported-by: Antoine Monnet <antoine@montane.tech>
Closes: https://lore.kernel.org/all/c66ae00a-e878-4af0-a05a-272e9574eaa5@montane.tech/
Signed-off-by: Andrey Golovko <andrey.golovko@gmail.com>
Link: https://patch.msgid.link/3e2751d1fb027bed0f09c88e5e56da8f@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

0 files changed, 0 insertions, 0 deletions