This email lists some known regressions in Linus' tree compared to 2.6.20....
Subject : libata: PATA UDMA/100 configured as UDMA/33
References : http://lkml.org/lkml/2007/2/20/294
http://www.mail-archive.com/linux-ide@xxxxxxxxxxxxxxx/msg04115.html
http://bugzilla.kernel.org/show_bug.cgi?id=8133
http://bugzilla.kernel.org/show_bug.cgi?id=8164
http://lkml.org/lkml/2007/3/21/330
Submitter : Fabio Comolli <fabio.comolli@xxxxxxxxx>
Plamen Petrov <plamen.petrov@xxxxxxxxxxxxx>
Laurent Riffard <laurent.riffard@xxxxxxx>
Lukas Hejtmanek <xhejtman@xxxxxxxxxxxx>
Handled-By : Tejun Heo <htejun@xxxxxxxxx>
Patch : http://thread.gmane.org/gmane.linux.ide/17444
Status : patch available