ASoC: tegra210_amx: simplify byte map get/put logic

The byte-map controls ("Byte Map N") already expose a value range of
[0, 256] to userspace via SOC_SINGLE_EXT(), where 256 is the
"disabled" sentinel. The driver stored this state as a byte-packed
u32 map[] array plus a separate byte_mask[] bitmap tracking which
slots were enabled, because 256 does not fit in a byte. As a result
get_byte_map() had to consult byte_mask[] to decide whether to
report the stored byte or 256, and put_byte_map() had to keep the
two arrays in sync on every write.

Store each slot as a u16 holding the control value directly
(0..255 enabled, 256 disabled). This is the native representation
for what userspace already sees, so get_byte_map() becomes a direct
return and put_byte_map() becomes a compare-and-store. The
hardware-facing packed RAM word and the OUT_BYTE_EN mask are now
derived on the fly inside tegra210_amx_write_map_ram() from the
slot array, which is the only place that needs to know about the
hardware layout.

The byte_mask buffer is allocated in probe() using devm_kcalloc()
with soc_data->byte_mask_size, so it scales to any SoC variant
without depending on chip-specific constants. It is zeroed and
recomputed each time write_map_ram() is called.

A new TEGRA_AMX_SLOTS_PER_WORD constant replaces the literal '4'
used for byte slots per RAM word, and BITS_PER_BYTE /
BITS_PER_TYPE() from <linux/bits.h> replace the literal '8' and
'32' shifts.

Slots are initialised to 256 in probe() so the default reported
value stays "disabled", matching previous behaviour. Values written
from userspace that fall outside [0, 255] are clamped to 256
("disabled") exactly as before -- no userspace-visible change.

As a side effect this also fixes a latent bug in the previous
put_byte_map(): because it compared the enable mask rather than the
stored byte, changing a slot from one enabled value to another
enabled value (e.g. 42 -> 99) would early-return without persisting
the new value, and the next CFG_RAM flush would still program the
old byte. The new implementation compares the stored value itself,
so this case is now handled correctly.

Addresses TODO left in tegra210_amx_get_byte_map().

Signed-off-by: Piyush Patle <piyushpatle228@gmail.com>
Link: https://patch.msgid.link/20260410200530.171323-3-piyushpatle228@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/tegra/tegra210_amx.c b/sound/soc/tegra/tegra210_amx.c
index d635046bbe81c078562c29ee98eb2fd5ef660347..930b080aec0ad7ef2b23e2a40970da6d20c54c9f 100644 (file)
--- a/sound/soc/tegra/tegra210_amx.c
+++ b/sound/soc/tegra/tegra210_amx.c
@@ -4,6 +4,7 @@
 //
 // tegra210_amx.c - Tegra210 AMX driver
 
+#include <linux/bits.h>
 #include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/io.h>
@@ -60,16 +61,35 @@ static const struct reg_default tegra264_amx_reg_defaults[] = {
 
 static void tegra210_amx_write_map_ram(struct tegra210_amx *amx)
 {
+       const unsigned int bits_per_mask = BITS_PER_TYPE(*amx->byte_mask);
        int i;
 
+       memset(amx->byte_mask, 0,
+              amx->soc_data->byte_mask_size * sizeof(*amx->byte_mask));
+
        regmap_write(amx->regmap, TEGRA210_AMX_CFG_RAM_CTRL + amx->soc_data->reg_offset,
                     TEGRA210_AMX_CFG_RAM_CTRL_SEQ_ACCESS_EN |
                     TEGRA210_AMX_CFG_RAM_CTRL_ADDR_INIT_EN |
                     TEGRA210_AMX_CFG_RAM_CTRL_RW_WRITE);
 
-       for (i = 0; i < amx->soc_data->ram_depth; i++)
+       for (i = 0; i < amx->soc_data->ram_depth; i++) {
+               u32 word = 0;
+               int b;
+
+               for (b = 0; b < TEGRA_AMX_SLOTS_PER_WORD; b++) {
+                       unsigned int slot = i * TEGRA_AMX_SLOTS_PER_WORD + b;
+                       u16 val = amx->map[slot];
+
+                       if (val >= 256)
+                               continue;
+
+                       word |= (u32)val << (b * BITS_PER_BYTE);
+                       amx->byte_mask[slot / bits_per_mask] |=
+                               1U << (slot % bits_per_mask);
+               }
                regmap_write(amx->regmap, TEGRA210_AMX_CFG_RAM_DATA + amx->soc_data->reg_offset,
-                            amx->map[i]);
+                            word);
+       }
 
        for (i = 0; i < amx->soc_data->byte_mask_size; i++)
                regmap_write(amx->regmap,
@@ -214,26 +234,8 @@ static int tegra210_amx_get_byte_map(struct snd_kcontrol *kcontrol,
        struct soc_mixer_control *mc =
                (struct soc_mixer_control *)kcontrol->private_value;
        struct tegra210_amx *amx = snd_soc_component_get_drvdata(cmpnt);
-       unsigned char *bytes_map = (unsigned char *)amx->map;
-       int reg = mc->reg;
-       int enabled;
-
-       enabled = amx->byte_mask[reg / 32] & (1 << (reg % 32));
 
-       /*
-        * TODO: Simplify this logic to just return from bytes_map[]
-        *
-        * Presently below is required since bytes_map[] is
-        * tightly packed and cannot store the control value of 256.
-        * Byte mask state is used to know if 256 needs to be returned.
-        * Note that for control value of 256, the put() call stores 0
-        * in the bytes_map[] and disables the corresponding bit in
-        * byte_mask[].
-        */
-       if (enabled)
-               ucontrol->value.integer.value[0] = bytes_map[reg];
-       else
-               ucontrol->value.integer.value[0] = 256;
+       ucontrol->value.integer.value[0] = amx->map[mc->reg];
 
        return 0;
 }
@@ -245,22 +247,20 @@ static int tegra210_amx_put_byte_map(struct snd_kcontrol *kcontrol,
                (struct soc_mixer_control *)kcontrol->private_value;
        struct snd_soc_component *cmpnt = snd_kcontrol_chip(kcontrol);
        struct tegra210_amx *amx = snd_soc_component_get_drvdata(cmpnt);
-       unsigned char *bytes_map = (unsigned char *)amx->map;
-       int reg = mc->reg;
-       int value = ucontrol->value.integer.value[0];
-       unsigned int mask_val = amx->byte_mask[reg / 32];
+       unsigned int value = ucontrol->value.integer.value[0];
 
-       if (value >= 0 && value <= 255)
-               mask_val |= (1 << (reg % 32));
-       else
-               mask_val &= ~(1 << (reg % 32));
+       /*
+        * Match the previous behaviour: any value outside [0, 255] is
+        * treated as the "disabled" sentinel (256). Negative values from
+        * userspace fold in through the unsigned cast and are caught here.
+        */
+       if (value > 255)
+               value = 256;
 
-       if (mask_val == amx->byte_mask[reg / 32])
+       if (amx->map[mc->reg] == value)
                return 0;
 
-       /* Update byte map and slot */
-       bytes_map[reg] = value % 256;
-       amx->byte_mask[reg / 32] = mask_val;
+       amx->map[mc->reg] = value;
 
        return 1;
 }
@@ -729,7 +729,7 @@ static int tegra210_amx_platform_probe(struct platform_device *pdev)
        struct device *dev = &pdev->dev;
        struct tegra210_amx *amx;
        void __iomem *regs;
-       int err;
+       int err, i;
 
        amx = devm_kzalloc(dev, sizeof(*amx), GFP_KERNEL);
        if (!amx)
@@ -751,17 +751,21 @@ static int tegra210_amx_platform_probe(struct platform_device *pdev)
 
        regcache_cache_only(amx->regmap, true);
 
-       amx->map = devm_kzalloc(dev, amx->soc_data->ram_depth * sizeof(*amx->map),
-                               GFP_KERNEL);
+       amx->map = devm_kcalloc(dev,
+                               amx->soc_data->ram_depth * TEGRA_AMX_SLOTS_PER_WORD,
+                               sizeof(*amx->map), GFP_KERNEL);
        if (!amx->map)
                return -ENOMEM;
 
-       amx->byte_mask = devm_kzalloc(dev,
-                                     amx->soc_data->byte_mask_size * sizeof(*amx->byte_mask),
-                                     GFP_KERNEL);
+       amx->byte_mask = devm_kcalloc(dev, amx->soc_data->byte_mask_size,
+                                     sizeof(*amx->byte_mask), GFP_KERNEL);
        if (!amx->byte_mask)
                return -ENOMEM;
 
+       /* Initialise all byte map slots as disabled (value 256). */
+       for (i = 0; i < amx->soc_data->ram_depth * TEGRA_AMX_SLOTS_PER_WORD; i++)
+               amx->map[i] = 256;
+
        tegra210_amx_dais[TEGRA_AMX_OUT_DAI_ID].capture.channels_max =
                        amx->soc_data->max_ch;
 

diff --git a/sound/soc/tegra/tegra210_amx.h b/sound/soc/tegra/tegra210_amx.h
index 50a237b197ba7197c3b52a59e87f10120d628038..420b62f0cf35bd546e220bd8960dcfda8fcea7d0 100644 (file)
--- a/sound/soc/tegra/tegra210_amx.h
+++ b/sound/soc/tegra/tegra210_amx.h
@@ -8,6 +8,8 @@
 #ifndef __TEGRA210_AMX_H__
 #define __TEGRA210_AMX_H__
 
+#include <linux/types.h>
+
 /* Register offsets from TEGRA210_AMX*_BASE */
 #define TEGRA210_AMX_RX_STATUS                 0x0c
 #define TEGRA210_AMX_RX_INT_STATUS             0x10
@@ -73,6 +75,7 @@
 #define TEGRA210_AMX_SOFT_RESET_SOFT_RESET_MASK                TEGRA210_AMX_SOFT_RESET_SOFT_EN
 
 #define TEGRA210_AMX_AUDIOCIF_CH_STRIDE                4
+#define TEGRA_AMX_SLOTS_PER_WORD               4
 #define TEGRA210_AMX_RAM_DEPTH                 16
 #define TEGRA210_AMX_MAP_STREAM_NUM_SHIFT      6
 #define TEGRA210_AMX_MAP_WORD_NUM_SHIFT                2
@@ -105,8 +108,8 @@ struct tegra210_amx_soc_data {
 
 struct tegra210_amx {
        const struct tegra210_amx_soc_data *soc_data;
-       unsigned int *map;
        unsigned int *byte_mask;
+       u16 *map;
        struct regmap *regmap;
 };