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    SubjectRe: [PATCH v5 03/16] media: rkisp1: Add user space ABI definitions
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    On 08/03/18 11:00, Jacob Chen wrote:
    > Hi Hans,
    >
    > 2018-02-07 20:00 GMT+08:00 Hans Verkuil <hverkuil@xs4all.nl>:
    >> On 12/29/17 08:52, Shunqian Zheng wrote:
    >>> From: Jeffy Chen <jeffy.chen@rock-chips.com>
    >>>
    >>> Add the header for userspace
    >>
    >> General note: I saw four cases where this documentation referred to the
    >> datasheet. Three comments on that:
    >>
    >> 1) You don't say which datasheet.
    >> 2) I assume the datasheet is under NDA?
    >
    > This datasheet can't be got by customers, even under NDA.

    OK. This should be mentioned somewhere.

    >
    >> 3) You do need to give enough information so a reasonable default can be
    >> used. I mentioned in an earlier review that creating an initial params
    >> struct that can be used as a templete would be helpful (or even
    >> required), and that would be a good place to put such defaults.
    >>
    >
    > It don't need a default config
    > For applcation writers, they can just init it with zero data, and only
    > set value for the part they concerned.

    This too should be clearly documented. This is very useful information for
    users of this API.

    >
    > As for ABI, i have checked there is no mismatches.
    > Those structures is 32 bit aligned both in 64bit/32bit env, since
    > there is no 64bit value.
    > "__attribute__ ((packed))" can avoid mismatches happen when we add a
    > 64bit value to those structures.
    >
    > As robin said, enums and bools are not guaranteed to be consistent
    > between different compiler, so it's a potential risk.
    > I have replace bools with unsigned char and enums with unsigned int.

    Excellent.

    Regards,

    Hans

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