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Re: Legacy IDE to be removed

Hi Adrian,

On 22/03/21 8:27 pm, John Paul Adrian Glaubitz wrote:
Hi Michael!

On 3/22/21 3:31 AM, Michael Schmitz wrote:
note that the libata driver for Falcon does not utilize interrupts due to the
interaction between IDE, SCSI and floppy hardware, the latter two also making
use of the ST-DMA chip which cannot be transparently checked for DMA completion.

Instead, the libata driver polls for IDE command completion. This may add a little
latency, but that's probably offset by the lack of contention between IDE and SCSI
drivers in mixed IDE / SCSI operation. In my tests, I haven't found any substantial
impact from the driver change (and I was quite sceptical of the libata driver performance).
Is this a fundamental limitation of libata that interrupts are not supported or just
a limitation of pata_falcon?

Only affects pata_falcon, and this was a design decision of the libata authors to not copy the clunky code that guards against simultaneous use of IDE and SCSI/floppy on Falcon.

No other IDE hardware supported by libata appears to require such locking. I'm sure it could be added back, but I won't open that particular can of worms.




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