I talked to the local expert on this and here are the answers he gave me:
Ok, I made changes in platform.h HFP_PCM_RX 5 -> 25.
Could you specify, please, the mixer_paths_sbc.xml location?
Path for mixer_paths_sbc.xml \device\qcom\msm8916_32
I'm trying to locate it but found nothing on latest LA.BR.1.2.4. In fact there is mixer_paths_sbc.xml located in /device/qcom/msm8916_32 but I doubt that is the one I'm looking for since the build will be msm8916_64, am I wrong?
all files are picked up from 8916_32 folder only
8916_64 only has files specific to 64 bit .. rest are copied from 8916_32 only . it is just a naming convention .. does not mean they are related to architecture
Otherwise I found also another one in /out/target/product/msm8916_64/system/etc/mixer_paths_sbc.xml... Should I check this one?
/out/target/product/msm8916_64/system/etc/mixer_paths_sbc.xml … this file will be generated , once you compiled your source code this is out folder which has compiled binaries and exe files and other .
Also, what exactly need to be modified in .xml file?
you need to add hfp voice call related changes , by default we don’t have these changes . Please add below changes in mixer_path_sbc.xml
<ctl name="QUAT_MI2S_RX Port Mixer INTERNAL_BT_SCO_TX" value="1" />
<ctl name="INTERNAL_BT_SCO_RX Audio Mixer MultiMedia6" value="1" />
<ctl name="MultiMedia6 Mixer TERT_MI2S_TX" value="1" />
<ctl name="HFP_INT_UL_HL Switch" value="1" />
<ctl name="QUAT_MI2S_RX_DL_HL Switch" value="1" />
<ctl name="Internal BTSCO SampleRate" value="16000" />
<path name="hfp-sco" />
Full disclosure: I am an employee of Qualcomm Canada, any opinions I may have expressed in this of any other post may not reflect the opinions of my employer.