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    SubjectRe: [PATCH take2] [POWERPC] i2c: adds support for i2c bus on 8xx
    Jochen Friedrich wrote:
    >>> diff --git a/arch/powerpc/boot/dts/mpc885ads.dts
    >>> b/arch/powerpc/boot/dts/mpc885ads.dts
    >>> index 8848e63..a526c02 100644
    >>> --- a/arch/powerpc/boot/dts/mpc885ads.dts
    >>> +++ b/arch/powerpc/boot/dts/mpc885ads.dts
    >>> @@ -213,6 +213,15 @@
    >>> fsl,cpm-command = <0080>;
    >>> linux,network-index = <2>;
    >>> };
    >>> +
    >>> + i2c@860 {
    >>> + device_type = "i2c";
    >>>
    >>
    >> No device_type.
    >>
    >
    > Why? Documentation/powerpc/booting-without-of.txt says for I2C interfaces
    > device_type is required and should be "i2c". Is this no longer true?

    booting-without-of.txt should be changed.

    >> Should be fsl,cpm-i2c. Is cpm2 i2c the same? If not, it should be
    >> fsl,cpm1-i2c. It's probably best to specify it anyway, along with
    >> fsl,mpc885-i2c.
    >
    > CPM2 i2c seems to be the same. However, i have no way to test this.

    OK, let's make the compatible "fsl,mpc885-i2c", "fsl,cpm1-i2c",
    "fsl,cpm-i2c".

    For now, match on the last one, but if any differences pop up, we have
    the more specific ones.

    > I noticed cpm1_set_pin32, but this function don't seem to set the
    > odr register. Will this be added? Then it would be:
    >
    > {CPM_PORTB, 26, CPM_PIN_OUTPUT | CPM_PIN_OPENDRAIN},
    > {CPM_PORTB, 27, CPM_PIN_OUTPUT | CPM_PIN_OPENDRAIN},
    >

    Ah, missed that -- there's opendrain support for port E, but I missed
    that port B had it as well. Feel free to add it.

    >> It's a 7-bit address... and are you sure that 0x7e is unique? Does this
    >> driver even support slave operation?
    >
    > It's in fact 0x7F << 1.

    Gah, I hate powerpc bit numbering, especially without the
    numbered-as-if-64-bit hack. I specifically looked at the manual before
    to see if it was shifted, saw "0-6", and concluded it wasn't. :-P

    > The same value is used in the 2.4 driver and
    > in u-boot, as well.

    That doesn't mean that this isn't a good time to review what the code is
    doing. :-)

    > Slave operation is not supported.

    If slave operation isn't supported, how is this value used?

    >> Why is an 8xx driver matching all i2c cpm (i.e. what about cpm2)?
    >
    > With the suggested change to use fsl,cpm-command, the driver should
    > be able to use both cpm1 and cpm2. The operation and structs for i2c
    > are identical. The only difference might be the hack^wsupport for
    > relocation.

    OK. Would that allow it to become one driver, rather than a wrapper and
    an algorithm?

    -Scott
    -
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