DMIC: Add support for passing unmute ramp time from topology

singalsu · lgirdwood · commit c328dd85f65b · 2019-06-17T21:47:31.000+01:00
The raw capture from digital microphones contain some DC signal
in the beginning. The DC compensation filter is set to be quite slow
to enable capturing lowest audio frequencies. The unmute gain ramp
is used in DMIC driver to conceal the DC signal. The required time
for clean looking start is is microphone model and platform dependent.
Also since not all applications are sensitive to DC waveform it is useful
to specify the ramp length in topology.

This patch adds to DMIC driver feature to define the unmute ramp
length in milliseconds. If the value from IPC is zero the existing
hard coded 400 ms long ramp is used. If the value is non-zero and
within min/max 10ms/1000ms limits the topology defined ramp length is
used.

The code uses the db2lin_fixed() function to convert the dB step
to a linear gain update coefficient. Also the hardcoded ramp definition
is simplified to use dB initial gain value and length in milliseconds
instead of magic looking numbers.

This patch also contains ABI minor version increase to 8.

Signed-off-by: Seppo Ingalsuo &lt;seppo.ingalsuo@linux.intel.com&gt;
diff --git a/src/drivers/intel/cavs/dmic.c b/src/drivers/intel/cavs/dmic.c
@@ -9,6 +9,7 @@
 #include <sof/interrupt.h>
 #include <sof/pm_runtime.h>
 #include <sof/math/numbers.h>
+#include <sof/math/decibels.h>
 #include <sof/audio/format.h>
 
 #if defined DMIC_HW_VERSION
@@ -95,15 +96,23 @@ struct pdm_controllers_configuration {
 /* Used in unmute ramp values calculation */
 #define DMIC_HW_FIR_GAIN_MAX ((1 << (DMIC_HW_BITS_FIR_GAIN - 1)) - 1)
 
-/* Hardwired log ramp parameters. The first value is the initial logarithmic
- * gain and the second value is the multiplier for gain to achieve the linear
- * decibels change over time. Currently the coefficient GM needs to be
- * calculated manually. The 400 ms ramp should ensure clean sounding start
- * with any microphone.
- * TODO: Add ramp characteristic passing via topology.
+/* Hardwired log ramp parameters. The first value is the initial gain in
+ * decibels. The second value is the default ramp time.
  */
-#define LOGRAMP_GI 33954 /* -90 dB, Q2.30*/
-#define LOGRAMP_GM 16814 /* Gives 400 ms ramp for -90..0 dB, Q2.14 */
+#define LOGRAMP_START_DB Q_CONVERT_FLOAT(-90, DB2LIN_FIXED_INPUT_QY)
+#define LOGRAMP_TIME_MS 400 /* Default ramp time in milliseconds */
+
+/* Limits for ramp time from topology */
+#define LOGRAMP_TIME_MIN_MS 10 /* Min. 10 ms */
+#define LOGRAMP_TIME_MAX_MS 1000 /* Max. 1s */
+
+/* Simplify log ramp step calculation equation with this constant term */
+#define LOGRAMP_CONST_TERM ((int32_t) \
+	((int64_t)-LOGRAMP_START_DB * DMIC_UNMUTE_RAMP_US / 1000))
+
+/* Fractional shift for gain update. Gain format is Q2.30. */
+#define Q_SHIFT_GAIN_X_GAIN_COEF \
+	(Q_SHIFT_BITS_32(30, DB2LIN_FIXED_OUTPUT_QY, 30))
 
 /* tracing */
 #define trace_dmic(__e, ...) \
@@ -152,12 +161,12 @@ static uint64_t dmic_work(void *data)
 	tracev_dmic("dmic_work()");
 	spin_lock(&dai->lock);
 
-	/* Increment gain with logaritmic step.
-	 * Gain is Q2.30 and gain modifier is Q2.14.
+	/* Increment gain with logarithmic step.
+	 * Gain is Q2.30 and gain modifier is Q12.20.
 	 */
 	dmic->startcount++;
-	dmic->gain = Q_MULTSR_32X32((int64_t)dmic->gain,
-				    LOGRAMP_GM, 30, 14, 30);
+	dmic->gain = q_multsr_sat_32x32(dmic->gain, dmic->gain_coef,
+					Q_SHIFT_GAIN_X_GAIN_COEF);
 
 	/* Gain is stored as Q2.30, while HW register is Q1.19 so shift
 	 * the value right by 11.
@@ -1034,6 +1043,8 @@ static int dmic_set_config(struct dai *dai, struct sof_ipc_dai_config *config)
 	struct dmic_configuration cfg;
 	struct decim_modes modes_a;
 	struct decim_modes modes_b;
+	int32_t unmute_ramp_time_ms;
+	int32_t step_db;
 	size_t size;
 	int i, j, ret = 0;
 	int di = dai->index;
@@ -1051,6 +1062,26 @@ static int dmic_set_config(struct dai *dai, struct sof_ipc_dai_config *config)
 		return -EINVAL;
 	}
 
+	/* Compute unmute ramp gain update coefficient. Use the value from
+	 * topology if it is non-zero, otherwise use default length.
+	 */
+	if (config->dmic.unmute_ramp_time)
+		unmute_ramp_time_ms = config->dmic.unmute_ramp_time;
+	else
+		unmute_ramp_time_ms = LOGRAMP_TIME_MS;
+
+	if (unmute_ramp_time_ms < LOGRAMP_TIME_MIN_MS ||
+	    unmute_ramp_time_ms > LOGRAMP_TIME_MAX_MS) {
+		trace_dmic_error("dmic_set_config(): Illegal ramp time = %d",
+				 unmute_ramp_time_ms);
+		return -EINVAL;
+	}
+
+	step_db = LOGRAMP_CONST_TERM / unmute_ramp_time_ms;
+	dmic->gain_coef = db2lin_fixed(step_db);
+	trace_dmic("dmic_set_config(): unmute_ramp_time_ms = %d",
+		   unmute_ramp_time_ms);
+
 	/*
 	 * "config" might contain pdm controller params for only
 	 * the active controllers
@@ -1197,7 +1228,9 @@ static void dmic_start(struct dai *dai)
 	trace_dmic("dmic_start()");
 	dmic->state = COMP_STATE_ACTIVE;
 	dmic->startcount = 0;
-	dmic->gain = LOGRAMP_GI; /* Initial gain value */
+
+	/* Initial gain value, convert Q12.20 to Q2.30 */
+	dmic->gain = Q_SHIFT_LEFT(db2lin_fixed(LOGRAMP_START_DB), 20, 30);
 
 	switch (dai->index) {
 	case 0:
diff --git a/src/include/ipc/dai-intel.h b/src/include/ipc/dai-intel.h
@@ -174,9 +174,10 @@ struct sof_ipc_dai_dmic_params {
 
 	uint32_t wake_up_time;      /**< Time from clock start to data (us) */
 	uint32_t min_clock_on_time; /**< Min. time that clk is kept on (us) */
+	uint32_t unmute_ramp_time;  /**< Length of logarithmic gain ramp (ms) */
 
 	/* reserved for future use */
-	uint32_t reserved[6];
+	uint32_t reserved[5];
 
 	/**< variable number of pdm controller config */
 	struct sof_ipc_dai_dmic_pdm_ctrl pdm[0];
diff --git a/src/include/kernel/abi.h b/src/include/kernel/abi.h
@@ -29,7 +29,7 @@
 
 /** \brief SOF ABI version major, minor and patch numbers */
 #define SOF_ABI_MAJOR 3
-#define SOF_ABI_MINOR 7
+#define SOF_ABI_MINOR 8
 #define SOF_ABI_PATCH 0
 
 /** \brief SOF ABI version number. Format within 32bit word is MMmmmppp */
diff --git a/src/include/sof/dmic.h b/src/include/sof/dmic.h
@@ -313,6 +313,7 @@ struct dmic_pdata {
 	struct task dmicwork;
 	int32_t startcount;
 	int32_t gain;
+	int32_t gain_coef;
 };
 
 extern const struct dai_driver dmic_driver;
