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ata_timing: ensure t->cycle is always correct

Russell King hit a case where quantisation errors accumulated such that
the cycle time was shorter than rather than equal to the active/recovery
time. The code already knows how to stretch times to fit the cycle time
but does not know about the reverse.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
hifive-unleashed-5.1
Alan Cox 2007-04-23 11:55:36 +01:00 committed by Jeff Garzik
parent c1c4e8d557
commit 4f701d1e9a
1 changed files with 6 additions and 0 deletions

View File

@ -2639,6 +2639,12 @@ int ata_timing_compute(struct ata_device *adev, unsigned short speed,
t->active += (t->cycle - (t->active + t->recover)) / 2;
t->recover = t->cycle - t->active;
}
/* In a few cases quantisation may produce enough errors to
leave t->cycle too low for the sum of active and recovery
if so we must correct this */
if (t->active + t->recover > t->cycle)
t->cycle = t->active + t->recover;
return 0;
}