Re: [PATCH v2.6.38-rc7] Revert "libata: ahci_start_engine compliant to AHCI spec"

On Sat, 14 May 2011 12:28:04 +0200, Tejun Heo said:

This reverts commit 270dac35c26433d06a89150c51e75ca0181ca7e4.

The commits causes command timeouts on AC plug/unplug.  It isn't yet
clear why.  As the commit was for a single rather obscure controller,
revert the change for now.

The problem was reported and bisected by Gu Rui in bug#34692.

 https://bugzilla.kernel.org/show_bug.cgi?id=34692

Also, reported by Rafael and Michael in the following thread.

 http://thread.gmane.org/gmane.linux.kernel/1138771

This also fixes the issue I had with a 10-second pause on my Dell Latitude E6500
laptop at boot while detecting the CD/DVD drive.