Re: "Fix ATAPI transfer lengths" causes CD writing regression

[Tejun Heo <htejun@gmail.com>]

Alan Cox wrote:
>> Maybe we could set a limit here. If the ATAPI device keeps DRQ=1 and
>> exceeds the limit, we consider it as HSM violation and have EH handle it.
> 
> On a DMA transfer its basically out of our control (and a PIO drain will
> lock some controllers solid until power cycle),

Do such controllers lock up on PIO draining after PIO transfers too?
Can you tell which are those controllers?

> but on PIO we know we
> never set a chunk size over 64K, so if we exceed 64K its time to apply a
> larger hammer

Draining is related to the amount of data the drive responds not to the
chunk size.  I agree 64k should be enough for most cases but I think
there can be corner cases where this doesn't hold.

Thanks.

-- 
tejun
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