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    SubjectRe: [PATCH 1/1][RESEND] Driver for the Atmel on-chip SSC on AT32AP and AT91.
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    hi Hans-Christian,

    > Just an example from sound/soc/at91/at91-ssc.c
    >
    > rcmr = (( ssc_p->rcmr_period << 24) & AT91_SSC_PERIOD)
    > | (( 1 << 16) & AT91_SSC_STTDLY)
    > | (( AT91_SSC_START_FALLING_RF ) & AT91_SSC_START)
    > | (( AT91_SSC_CK_RISING ) & AT91_SSC_CKI)
    > | (( AT91_SSC_CKO_NONE ) & AT91_SSC_CKO)
    > | (( AT91_SSC_CKS_DIV ) & AT91_SSC_CKS);

    Well, I didn't write the above, so it's more complex than it needs to
    be.

    For bitfields where the user can input any value we would usually add to
    the header:
    #define AT91_SSC_STTDLY_(x) ((x) << 16)
    #define AT91_SSC_PERIOD_(x) ((x) << 24)

    Then it can simply be re-written as:

    rcmr = AT91_SSC_PERIOD(ssc_p->rcmr_period)
    | AT91_SSC_STTDLY(1)
    | AT91_SSC_START_FALLING_RF
    | AT91_SSC_CK_RISING
    | AT91_SSC_CKO_NONE
    | AT91_SSC_CKS_DIV;


    > Would with the header style for atmel-ssc be:
    >
    > rcmr = SSC_BF(RCMR_PERIOD, ssc_p->rcmr_period)
    > | SSC_BF(RCMR_STTDLY, 1)
    > | SSC_BF(RCMR_START, 4)
    > | SSC_BF(RCMR_CKI, 1)
    > | SSC_BF(RCMR_CKO, 0)
    > | SSC_BF(RCMR_CKS, 0);
    >
    > I find the latter more readable and compact, the user also does not need
    > to know the offset of the different bit-fields.

    But the user does then constantly have to refer to the datasheet to
    determine what CKI = 1 or CKS = 0 means.


    Regards,
    Andrew Victor


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