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DMIC: Increase start gain ramp length to 400 ms 

This patch updates the gain update coefficient to achieve
a longer ramp time. The previous 300 ms long ramp was not
enough to conceal all of the slow DC component settling seen
in the beginning of DMIC capture.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>
This commit is contained in:
Seppo Ingalsuo 2019-05-27 18:28:06 +03:00 committed by Janusz Jankowski
parent b4d292d75f
commit ec6ed1ac15
1 changed files with 3 additions and 3 deletions
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6
src/drivers/intel/cavs/dmic.c
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@ -122,12 +122,12 @@ struct pdm_controllers_configuration {
/* 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 300 ms ramp should ensure clean sounding start with
* any microphone. However it is likely unnecessarily long for machine hearing.
* calculated manually. The 400 ms ramp should ensure clean sounding start
* with any microphone.
* TODO: Add ramp characteristic passing via topology.
*/
#define LOGRAMP_GI 33954 /* -90 dB, Q2.30*/
#define LOGRAMP_GM 16959 /* Gives 300 ms ramp for -90..0 dB, Q2.14 */
#define LOGRAMP_GM 16814 /* Gives 400 ms ramp for -90..0 dB, Q2.14 */
/* tracing */
#define trace_dmic(__e, ...) \