Re: [PATCH] sata_nv,ahci: add the ahci legacy mode support to sata_nv

["peer chen" <peerchen@gmail.com>]

Ok,I agree to use AHCI driver for our AHCI controllers no matter their
class codes are IDE/RAID/AHCI. But for those new or upcoming AHCI
controller which DIDs are not included in ahci.c and also IDE/RAID
mode being set in BIOS, no driver will be loaded currently, so I hope
the first patch http://lkml.org/lkml/2007/10/8/93 can be appied for
this case. Any comments?

2007/10/19, Jeff Garzik <jeff@garzik.org>:
> peer chen wrote:
> > I hope one of the following patches can be merged to 2.6.24.
> > ==========================
> > http://lkml.org/lkml/2007/10/8/93
> > http://lkml.org/lkml/2007/9/25/20
>
> Unfortunately I do not feel like this is the right course of action.
>
> Experience from Intel platforms tells us that our users get very unhappy
> when their silicon supports AHCI mode, but they are forced into using a
> less-performant mode.  A popular example is an <unnamed> OEM whose BIOS
> had no method whatsoever for enabling AHCI -- didn't even program the
> PCI BAR -- even though tests showed the AHCI mode worked just fine when
> manually programmed.
>
> AHCI is more likely to provide a /stable/ Serial ATA experience, because
> the silicon deals primarily with sending and receiving FIS's, and not
> much else.  In constrast, experience has shown the legacy IDE interface
> to be a less reliable method of SATA support.  And certainly AHCI is
> much, much faster with less per-command overhead.
>
> Given that AHCI is both faster and more stable, I feel it is the best
> policy to enable AHCI when the hardware supports it, regardless of PCI
> class code (IDE, SATA, or RAID).
>
>
> > Yes, I agree to set the 'swncq' as default for 2.6.24, after all, for
> > our server customers, stability is far more important than the new
> > feature no matter the problem is caused by drive or controller.
>
> Agreed.  Done!
>
>        Jeff
>
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