On Fri, 25 Mar 2005 20:48:21 -0500, Brett Russ <[EMAIL PROTECTED]> wrote: > Jeff Garzik wrote: > > Chris Hann wrote: > >> ide-disk.c checks csfo bit 0 to see if the cache is available on a device > >> hdregs.h maps csfo to word 129 of the Identify Device information > >> the latest ATA documentation, e00159r3 Mandatory IDENTIFY DEVICE > >> information, says words 129-159 are Vendor specific. > >> > >> Why is the driver switching on cache operations based on a word that > >> has nothing to do with cache? > > > > > > Good question... I would guess that it's some pre-ATA4 legacy magic, > > but that's just a guess. > > I just checked the specs for ATA[134567] (didn't have 2) and all of them > show word 129 as vendor specific, as Chris found. > > The code that's in libata-dev shows in idedisk_setup(): > > /* write cache enabled? */ > if ((id->csfo & 1) || (id->cfs_enable_1 & (1 << 5))) > drive->wcache = 1; > > Bart, what's the point of the csfo bit check? If it's specific to one > non-ATA compliant device shouldn't it be testing something else along > with that bit?
AFAIR it was Alan who added this code, so lets ask him :) Alan? - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
