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>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 227399e..4e1df53 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2639,6 +2639,12 @@
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;
}