Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 9 Nov 2022 20:40:48 +0100
From:   Ahelenia =?utf-8?Q?Ziemia=C5=84ska?= 
        <nabijaczleweli@nabijaczleweli.xyz>
To:     James Bottomley <jejb@linux.ibm.com>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Federico Vaga <federico.vaga@vaga.pv.it>,
        Alex Shi <alexs@kernel.org>,
        Yanteng Si <siyanteng@loongson.cn>,
        Hu Haowen <src.res@email.cn>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        linux-doc-tw-discuss@lists.sourceforge.net,
        linux-scsi@vger.kernel.org
Subject: Re: [PATCH v2 14/15] scsi: ncr53c8xx: replace CCB_MAGIC with bool
 busy
Message-ID: <20221109194048.hcs65yzpsgvek73m@tarta.nabijaczleweli.xyz>
References: <cover.1667330271.git.nabijaczleweli@nabijaczleweli.xyz>
 <27cefe163e602f7d5b35ba2e966dccf9109798f9.1667330271.git.nabijaczleweli@nabijaczleweli.xyz>
 <44fa41b4d69219b89e805d572df486c4dda77f08.camel@linux.ibm.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
        protocol="application/pgp-signature"; boundary="a6dqxib67q7dhbvf"
Content-Disposition: inline
In-Reply-To: <44fa41b4d69219b89e805d572df486c4dda77f08.camel@linux.ibm.com>
User-Agent: NeoMutt/20220429
Precedence: bulk


--a6dqxib67q7dhbvf
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Fri, Nov 04, 2022 at 03:57:20PM -0400, James Bottomley wrote:
> On Wed, 2022-11-02 at 00:06 +0100, Ahelenia Ziemia=C5=84ska wrote:
> [...]
> > @@ -4356,7 +4347,7 @@ static int ncr_queue_command (struct ncb *np,
> > struct scsi_cmnd *cmd)
> >  	*/
> > =20
> >  	/* activate this job.  */
> > -	cp->magic		=3D CCB_MAGIC;
> > +	cp->busy		=3D true;
> > =20
> >  	/*
> >  	**	insert next CCBs into start queue.
>=20
> Are you sure this is just an internal magic number?  The way these old
> scripts engines used to work is that the CCB array forms a mailbox and
> the card continually scans the mailbox to see if it has any work to do.
> These magic values are often a signal to the card that the CCB array
> contains a valid entry it hasn't seen and it should work on it, so the
> card might be expecting to see this full 32 bit value.

AFAICT this is an internal flag: in FreeBSD, whence this is copied, this
driver is introduced in 37bd2c9c33d9684c0bf650e02579ebb329724d6a[1],
and AFAICT it's used in exactly the same way as it is here; the manual[2]
doesn't mention it at all; neither do the scripts; and the layout is
vastly different between there and current Linux; so I'm happy to
conclude it's not used by the device, I think?

1: https://cgit.freebsd.org/src/commit/?id=3D37bd2c9c33d9684c0bf650e02579eb=
b329724d6a
2: http://bitsavers.trailing-edge.com/components/ncr_symbios/scsi/53C810/53=
C810_PCI-SCSI_IO_Processor_Data_Manual_May1993.pdf

--a6dqxib67q7dhbvf
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=vTv4
-----END PGP SIGNATURE-----

--a6dqxib67q7dhbvf--