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    SubjectRe: [PATCH 3/3] Add disk hotswap support to libata RESEND #2
    Lukasz Kosewski wrote:
    > On 9/6/05, Jim Ramsay <jim.ramsay@gmail.com> wrote:
    >
    >>However, I have seen the occasion where a single IRQ is used to signal
    >>both a DMA completion AND a hotplug event. Of course in this case the
    >>hotplug event itself would be ignored completely.
    >>
    >>So I would recommend getting rid of that check entirely.
    >
    >
    > Hey Jim,
    >
    > Not that I disbelieve you, but do you have an example of a controller
    > where this happens? I've done a lot of testing and never seen this...

    I missed the beginning of this discussion,
    but here's a data point:

    The QStor SATA/RAID controller hardware fully supports hotplug
    (and NCQ, TCQ, Host-Queuing, RAID 0/1/10, PM, etc..).

    It uses a single interrupt for all onboard events from the four channels.
    An internal "status FIFO" provides a readout for the interrupt handler
    of recent happenings, in sequence, mixing together DMA-completions
    with hotplug-events (insert, removal) and various fault-conditions.

    All of this is supported in the out-of-tree qstor driver,
    but only simple single-IO is supported by sata_qstor at present.

    Dunno if that info is of any use to you in hotplug considerations.
    Once the libata infrastructure for hotplug is in place,
    I *may* experiment with adding that functionality to sata_qstor.

    Cheers
    -
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