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How to enable DM36x voice codec 8-word EDMA transfer

Mingqian
Intellectual 635 points


Hi all,

    In DM36x voice codec user guide(SPRUF19B), register field RFIFOMD in VC_CTRL can be set to 0 so that eight words of data can be read from RFIFO access register each time VCREVT occurs.

    I find that in the kernel that comes with dvsdk_2_10_01_18(i.e, MVL), RFIFOMD is set to 1 thus EDMA is heavily used.

    If I change the file($KERNEL_ROOT/sound/soc/davinci-i2s-vcif.h) as follows:

    - #define DAVINCI_VCIF_CTRL_MASK 0x5500

    + #define DAVINCI_VCIF_CTRL_MASK 0x5100

    I find that edma is used less, but the data gets transferred is not right. It is because the edma transfer parameters are not correctly modified.

    I am not quite clear of the edma part. So could anyone here help me with the modification needed to use 8-word RFIFO access.

   Many thanks.


Rafael