From: Brett Russ <russb@emc.com>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: Chris Hann <chann94501@yahoo.com>,
linux-ide list <linux-ide@vger.kernel.org>,
Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Subject: Re: hdregs.h puts csfo at word 129 - wrong, that's vendor specific
Date: Fri, 25 Mar 2005 20:48:21 -0500 [thread overview]
Message-ID: <4244BF65.6070109@emc.com> (raw)
In-Reply-To: <42437F78.8090703@pobox.com>
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
next prev parent reply other threads:[~2005-03-26 1:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-25 1:28 hdregs.h puts csfo at word 129 - wrong, that's vendor specific Chris Hann
2005-03-25 3:03 ` Jeff Garzik
2005-03-26 1:48 ` Brett Russ [this message]
2005-03-26 2:01 ` Bartlomiej Zolnierkiewicz
2005-03-27 13:58 ` Alan Cox
2005-04-13 22:18 ` Brett Russ
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4244BF65.6070109@emc.com \
--to=russb@emc.com \
--cc=bzolnier@gmail.com \
--cc=chann94501@yahoo.com \
--cc=jgarzik@pobox.com \
--cc=linux-ide@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.