From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brett Russ Subject: Re: hdregs.h puts csfo at word 129 - wrong, that's vendor specific Date: Wed, 13 Apr 2005 18:18:58 -0400 Message-ID: <425D9AD2.4060808@emc.com> References: <4243693F.9090008@yahoo.com> <42437F78.8090703@pobox.com> <4244BF65.6070109@emc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mailhub.lss.emc.com ([168.159.2.31]:60898 "EHLO mailhub.lss.emc.com") by vger.kernel.org with ESMTP id S261159AbVDMWVB (ORCPT ); Wed, 13 Apr 2005 18:21:01 -0400 In-Reply-To: <4244BF65.6070109@emc.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: andre@linux-ide.org Cc: Jeff Garzik , Chris Hann , linux-ide list , Bartlomiej Zolnierkiewicz This appears to have been dropped. The last word (http://article.gmane.org/gmane.linux.ide/3588) was from Alan who said Andre would know the history. Andre, can you help answer? Thanks BR Brett Russ 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? > > BR > - > To unsubscribe from this list: send the line "unsubscribe linux-ide" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html