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SubjectRe: [PATCH] ata-sff: always map page before data transfer
> I don't understand all the factors at play here, so thoughts are definitely
> welcome.

I don't fully understand the old code either. One thing that is weird
is the "use a bounce buffer comment" which doesn't make any sense.

The other is the local_irq_save, which isn't really needed for
kmap_atomic to start with, but maybe that's the reason why the original
author didn't want to do it unconditionally?

So based on that:

> + /* FIXME: use a bounce buffer */

drop this comment..

> + local_irq_save(flags);

.. remove the local_irq_save/local_irq_restore ..

> + /* do the actual data transfer */
> + ap->ops->sff_data_xfer(qc, buf + offset, qc->sect_size,
> + do_write);

.. and a nice alittle cleanup move the do_write onto the previous line.

> + /* FIXME: use bounce buffer */
> + local_irq_save(flags);
> + buf = kmap_atomic(page);
>
> + /* do the actual data transfer */
> + consumed = ap->ops->sff_data_xfer(qc, buf + offset,
> + count, rw);

And same here.

And we should be fine.

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