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    SubjectRe: [PATCH] Topcliff PHUB: Generate PacketHub driver
    On Tuesday 08 June 2010, Masayuki Ohtake wrote:
    > We are studying your indication.
    > > My feeling is that this ioctl interface is too
    > > low-level in general. You only export access to specific
    > > registers, not to functionality exposed by them.
    > > The best kernel interfaces are defined in a way that
    > > is independent of the underlying hardware and
    > > convert generic commands into device specific commands.
    > I have a question.
    > We don't know 'generic commands' concretely.
    > Let me know 'generic commands' in detail.

    I have not seen the application using the driver, but
    a better abstraction IMHO would be to take an abstraction
    you have in your application and move it into the kernel.

    I can be more specific if you tell me where to find the
    source of the application. Generally speaking, you'd
    transform a function like

    /* the function that knows how to do 'this' */
    int phub_do_this(int phub_fd, unsigned long arg)
    struct pch_phub_req req = {
    .addr_offset = SOME_ADDR_OFF,
    ioctl(fd, IOCTL_PHUB_READ_REG, &req);

    if ( & SOME_BITS)
    return ERROR;

    req.addr_offset = ANOTHER_ADDR_OFF; = arg | REALLY_DO_IT_BITMASK;

    ioctl(fd, IOCTL_PHUB_WRITE_REG, &req);

    return 0;

    into another function that does the same thing but
    without knowing anything about the registers:

    /* the same function on the abstract interface */
    int phub_do_this_new(int phub_fd, unsigned long arg)
    return ioctl(phub_fd, IOCTL_PHUB_DO_THIS, &arg);


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      Last update: 2010-06-08 11:33    [W:0.020 / U:0.596 seconds]
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