Re: ahci: work around ATI SB600 h/w quirk

From: Jens Axboe
Date: Thu Mar 06 2008 - 03:18:41 EST


On Thu, Mar 06 2008, Linux Kernel Mailing List wrote:
> Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a878539ef994787c447a98c2e3ba0fe3dad984ec
> Commit: a878539ef994787c447a98c2e3ba0fe3dad984ec
> Parent: 6ddd68615ae9b21096545d7d6ab0f04113ae8b42
> Author: Jeff Garzik <jeff@xxxxxxxxxx>
> AuthorDate: Thu Feb 28 15:43:48 2008 -0500
> Committer: Jeff Garzik <jeff@xxxxxxxxxx>
> CommitDate: Wed Mar 5 07:53:06 2008 -0500
>
> ahci: work around ATI SB600 h/w quirk
>
> This addresses the recent ATI SB600 errata, where the hardware does
> not like 256-length PRD entries during FPDMA (aka NCQ).
>
> It hurts performance on SB600, but it is more important to get a
> correct patch eliminating the data corruption/lockups, and then later
> on tune for performance.
>
> We simply limit each command to a maximum of 255 sectors, on SB600.

Why not limit it to 255 segments, if that's the real issue?

--
Jens Axboe

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