FreeCalypso > hg > freecalypso-reveng
view compal/audio/omr-via-headset @ 380:a66cb88c5f77
compal/audio/omr-via-headset: result of experiment
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Sun, 10 Oct 2021 21:48:24 +0000 |
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Follow-up on the experiments described in the omr-guide article: I connected the headset jack serial cable to a C139 phone that has a SIM inserted, and booted it up with a real GSM network connection. And then I made a test call. There is a headset icon displayed on the home screen, and no sounds emanate from the built-in earpiece speaker, so it is definitely in headset mode. However, by getting into the active call state, I was able to access the volume control screen, and I got an omr reading of d_vbdctrl DSP API word at each volume level. Here they are: Level d_vbdctrl VBDCTRL Vol gain PGA gain Total ------------------------------------------------------------------------------ 0 0x018C 0x006 -12 dB 0 dB -12 dB 1 0x020C 0x008 -12 dB 2 dB -10 dB 2 0x028C 0x00A -12 dB 4 dB -8 dB 3 0x030C 0x00C -12 dB 6 dB -6 dB 4 0x1A4C 0x069 -6 dB 3 dB -3 dB 5 0x1ACC 0x06B -6 dB 5 dB -1 dB 6 0x09CC 0x027 0 dB 1 dB 1 dB 7 0x0A8C 0x02A 0 dB 4 dB 4 dB Additional observation: the volume levels listed above exist only in the active call state: when a call ends, the fw switches to fixed level 4 for keybeeps and whatnot. When a new call begins, the fw restores the last set in-call volume level. Further observation: DL FIR coefficients stay the same at all 8 volume levels: 0x7FFF in coefficient 0, zeros in all others. Thus Compal's hack of adding another 6 dB of gain via the FIR block is unaffected by volume control, and no frequency curve transformation is ever applied, at least in headset mode. Regarding AEC: the reading of 0x03C7 from d_aec_ctrl when breaking in with tfc139 definitely seemed suspicious. Reading the same word via omr, we get 0x0226 while in an active call and 0x03A7 after the call ends. Furthermore, we can catch a little bit of trace output related to headset insertion if we have rvinterf running and do the **16379# trace enable step before inserting the serial cable into the headset jack, and we see this trace message: L1: AEC_R <fn> 03a6 0001 0014 4ccc 59ad 7500 0000 1000 1000 Thus it looks like C139 headset mode AEC configuration is: * AEC enabled (bit 1 in d_aec_ctrl) * noise suppression enabled (bit 2 in d_aec_ctrl) * NS level bits (d_aec_ctrl[6:5]) are set to 0x20 * New AEC parameter words are 0001 0014 4ccc 59ad 7500 0000 1000 1000 VBC registers during active call: Register DSP API word 10-bit register value ----------------------------------------------------- VBCTRL1 0x0110 0x004 VBCTRL2 0x01D6 0x007 VBUCTRL 0x6CCE 0x1B3 Notice VBUCTRL diff: we read 0x1B3 (9 dB uplink gain) when we are in an active call, but 0x1B2 (8 dB uplink gain) otherwise.