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    SubjectRe: [PATCH 1/1] megaraid_{mm,mbox}: fix a bug in reset handler
    Andrew Morton <akpm@osdl.org> wrote:
    >
    > > @@ -2918,12 +2933,12 @@
    > > wmb();
    > > WRINDOOR(raid_dev, raid_dev->mbox_dma | 0x1);
    > >
    > > - for (i = 0; i < 0xFFFFF; i++) {
    > > + for (i = 0; i < 0xFFFFFF; i++) {
    > > if (mbox->numstatus != 0xFF) break;
    > > rmb();
    > > }
    >
    > Oh my. That's an awfully long interrupts-off spin.

    And if that mbox is in main memory, the duration of this spin will vary by
    a factor of many tens across all the different machines on which this
    driver must operate.

    Careful use of ndelay() or udelay() would fix that.
    -
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