tree ed6f4ef6d78fe448aa8ec782b4eef6f83364aaa5
parent 78ab88f04f44bed566d51dce0c7cbfeff6449a06
author Tejun Heo <htejun@gmail.com> 1209603788 +0900
committer Jeff Garzik <jgarzik@redhat.com> 1210088033 -0400

ata_piix: verify SIDPR access before enabling it

On certain configurations (certain macbooks), even though all the
conditions for SIDPR access described in the datasheet are met,
actually reading those registers just returns 0 and have no effect on
write.  Verify SIDPR is actually working before enabling it.

This is reported by Ryan Roth in bz#10512.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Ryan Roth <ryan.roth@ch2m.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>