[PATCH v3 0/2] ASoC: tegra210: simplify ADX/AMX byte map get/put logic

[Piyush Patle]

The Tegra210 ADX and AMX drivers both keep their "Byte Map N" ALSA
control state as a byte-packed u32 map[] array along with a separate
byte_mask[] bitmap. This is because the control range exposed to
userspace is [0, 256], where 256 is the "disabled" sentinel and
does not fit in a byte, so the two arrays have to be cross-checked
on every get()/put().

This series stores each slot as a u16 holding the user-visible
value directly, turning get_byte_map() into a direct return and
put_byte_map() into a compare-and-store. The hardware-facing packed
RAM word and the IN_BYTE_EN / OUT_BYTE_EN enable masks are computed
on the fly inside each write_map_ram() callback, which is the only
place that needs to know the hardware layout. The byte_mask[] field
is kept in the driver struct but allocated dynamically in probe()
using devm_kcalloc() with soc_data->byte_mask_size, and zeroed +
recomputed on each write_map_ram() call.

There is no userspace-visible ABI change. Control declarations,
ranges, initial values and handling of out-of-range writes is
preserved by treating values outside [0, 255] as disabled (256),
matching previous behavior. As a side effect each patch also fixes
a latent bug in put_byte_map() where an enabled-to-enabled value
change was not persisted.

The packed RAM word construction is also updated to ensure the shift
operates on a u32 value, avoiding potential undefined behavior due
to signed integer promotion.

Addresses TODO comments left in tegra210_{adx,amx}_get_byte_map().

Changes since v2:
 - Move byte_mask allocation back to probe() with devm_kcalloc()
   using soc_data->byte_mask_size; revert write_map_ram() to void
   and runtime_resume() to returning 0. Suggested by Jon Hunter.
 - Fix bits_per_mask: use BITS_PER_TYPE(*byte_mask) instead of the
   incorrect BITS_PER_TYPE(*map) * BITS_PER_BYTE. Reported by
   Mark Brown.
 - Drop <linux/slab.h> include (no longer needed without kfree).

Changes since v1:
 - Use dynamic sizing via soc_data->byte_mask_size instead of
   chip-specific constants. Suggested by Sheetal.
 - Replace magic numbers with TEGRA_{ADX,AMX}_SLOTS_PER_WORD
   and use BITS_PER_BYTE / BITS_PER_TYPE(). Suggested by Sheetal.
 - Add <linux/bits.h> include.

Patch 1/2: ASoC: tegra210_adx: simplify byte map get/put logic
Patch 2/2: ASoC: tegra210_amx: simplify byte map get/put logic

Piyush Patle (2):
  ASoC: tegra210_adx: simplify byte map get/put logic
  ASoC: tegra210_amx: simplify byte map get/put logic

 sound/soc/tegra/tegra210_adx.c | 85 ++++++++++++++++++----------------
 sound/soc/tegra/tegra210_adx.h |  5 +-
 sound/soc/tegra/tegra210_amx.c | 82 ++++++++++++++++----------------
 sound/soc/tegra/tegra210_amx.h |  5 +-
 4 files changed, 96 insertions(+), 81 deletions(-)

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2.43.0