feat(es8311): add digital input gain and restore 42dB HW max for ES3C28P/35P

- Add input-gain-percent property (0..2000, default 100) to everest,es8311 binding
- Extend Es8311Config with input_gain_percent, Es8311Data with input_gain float
- Implement get_input_gain_multiplier() so audio-stream can apply digital boost on top of HW gain
- Change HW gain mapping 100% -> 42dB (was 24dB) to restore +30dB behavior remembered from pre audio-stream driver (ES8311 supports 0/6/12/18/24/30/36/42 per vendor)
- Validate percent <=2000 in start_device()
- Set ES3C28P (2.8" color) and ES3C35P (3.5" color) DTS to input-gain-percent = <100> (no extra digital, pure HW 42dB max, software volume can lower)
- Fixes quiet mic even at 100% and allows tunable digital boost via devicetree for boards with quiet MEMS capsules

Devices/es3c28p/es3c28p.dts

@@ -91,6 +91,7 @@
 			compatible = "everest,es8311";
 			reg = <0x18>;
 			i2s = <&i2s0>;
+			input-gain-percent = <100>;
 		};
 	};
 

Devices/es3c35p/es3c35p.dts

@@ -88,6 +88,7 @@
 			compatible = "everest,es8311";
 			reg = <0x18>;
 			i2s = <&i2s0>;
+			input-gain-percent = <100>;
 		};
 	};
 

Drivers/es8311-module/bindings/everest,es8311.yaml

@@ -9,3 +9,7 @@ properties:
     type: phandle
     required: true
     description: "I2S controller device that carries audio data"
+  input-gain-percent:
+    type: int
+    default: 100
+    description: "Extra digital gain multiplier applied by audio_stream on top of the ES8311's own 24dB hardware ADC gain, as an integer percentage (100 = 1.0x / no extra boost). For quiet MEMS mic capsules that are still quiet even at max hardware gain."

Drivers/es8311-module/include/drivers/es8311.h

@@ -25,6 +25,14 @@ struct Es8311Config {
     uint8_t address;
     /** I2S controller device that carries audio data */
     struct Device* i2s_device;
+    /**
+     * Extra fixed digital gain multiplier applied by audio_stream on top of the ES8311's
+     * own hardware ADC gain (0..24dB), as an integer percentage (100 = 1.0x / no extra boost).
+     * Small MEMS mic capsules can still sound quiet even near max hardware gain; this is for
+     * boards where 24dB hardware gain alone isn't enough. devicetree has no float property type,
+     * hence the x100 integer encoding.
+     */
+    uint16_t input_gain_percent;
 };
 
 #ifdef __cplusplus

Drivers/es8311-module/source/es8311.cpp

@@ -31,6 +31,7 @@ struct Es8311Data {
     bool is_open = false;
     AudioCodecDirection open_direction = AUDIO_CODEC_DIR_BOTH;
     esp_codec_dev_sample_info_t open_sample_info = {};
+    float input_gain = 1.0f;
 };
 
 #define GET_CONFIG(device) (static_cast<const Es8311Config*>((device)->config))
@@ -164,8 +165,8 @@ error_t set_volume(Device* device, AudioCodecDirection direction, float volume_p
     }
 
     if (direction == AUDIO_CODEC_DIR_INPUT) {
-        // ES8311 ADC gain range is roughly 0..24 dB; map 0..100% linearly onto it.
-        float db = (volume_percent / 100.0f) * 24.0f;
+        // ES8311 ADC gain supports 0..42dB (0,6,12,18,24,30,36,42) – max hardware to restore old +30dB+ behavior
+        float db = (volume_percent / 100.0f) * 42.0f;
         return (esp_codec_dev_set_in_gain(data->codec_device, db) == ESP_CODEC_DEV_OK) ? ERROR_NONE : ERROR_RESOURCE;
     }
 
@@ -192,7 +193,8 @@ error_t get_volume(Device* device, AudioCodecDirection direction, float* volume_
         if (esp_codec_dev_get_in_gain(data->codec_device, &db) != ESP_CODEC_DEV_OK) {
             return ERROR_RESOURCE;
         }
-        *volume_percent = (db / 24.0f) * 100.0f;
+        *volume_percent = (db / 42.0f) * 100.0f;
+        if (*volume_percent > 100.0f) *volume_percent = 100.0f;
         return ERROR_NONE;
     }
 
@@ -255,6 +257,12 @@ error_t get_capabilities(Device* device, AudioCodecDirection* supported_directio
     return ERROR_NONE;
 }
 
+error_t get_input_gain_multiplier(Device* device, float* gain) {
+    auto* data = GET_DATA(device);
+    *gain = data->input_gain;
+    return ERROR_NONE;
+}
+
 static const struct AudioCodecApi API = {
     .open = open,
     .close = close,
@@ -267,7 +275,7 @@ static const struct AudioCodecApi API = {
     .get_native_sample_rate = get_native_sample_rate,
     .get_native_channels = get_native_channels,
     .get_capabilities = get_capabilities,
-    .get_input_gain_multiplier = nullptr,
+    .get_input_gain_multiplier = get_input_gain_multiplier,
 };
 
 // endregion
@@ -277,6 +285,11 @@ static const struct AudioCodecApi API = {
 error_t start_device(Device* device) {
     const auto* config = GET_CONFIG(device);
 
+    if (config->input_gain_percent > 2000) {
+        LOG_E(TAG, "Invalid input_gain_percent %u (must be 0..2000)", config->input_gain_percent);
+        return ERROR_RESOURCE;
+    }
+
     auto* i2c_controller = device_get_parent(device);
     if (i2c_controller == nullptr || device_get_type(i2c_controller) != &I2C_CONTROLLER_TYPE) {
         LOG_E(TAG, "Parent is not an I2C controller");
@@ -290,6 +303,9 @@ error_t start_device(Device* device) {
     }
 
     auto* data = new Es8311Data();
+    data->input_gain = (float) config->input_gain_percent / 100.0f;
+    if (data->input_gain < 0.0f) data->input_gain = 1.0f;
+    if (config->input_gain_percent == 0) data->input_gain = 1.0f; // default when not set (devicetree default 100, but 0 means unset)
 
     data->ctrl_if = audio_codec_adapter_new_i2c_ctrl(i2c_controller, config->address);
     data->data_if = audio_codec_adapter_new_i2s_data(i2s_controller);