From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: PMP and SEMB messages to SEP Date: Mon, 17 Jan 2011 18:20:54 +0100 Message-ID: <20110117172054.GJ27123@htj.dyndns.org> References: <20110113192558.GE16039@MAIL.13thfloor.at> <20110114142018.GA978@htj.dyndns.org> <20110114165957.GH16039@MAIL.13thfloor.at> <20110114170407.GE978@htj.dyndns.org> <20110114173759.GI16039@MAIL.13thfloor.at> <20110117154042.GG27123@htj.dyndns.org> <1295281131.3015.44.camel@mulgrave.site> <20110117171312.GL16039@MAIL.13thfloor.at> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-fx0-f46.google.com ([209.85.161.46]:63210 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753440Ab1AQRU7 (ORCPT ); Mon, 17 Jan 2011 12:20:59 -0500 Content-Disposition: inline In-Reply-To: <20110117171312.GL16039@MAIL.13thfloor.at> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Herbert Poetzl Cc: James Bottomley , linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org On Mon, Jan 17, 2011 at 06:13:12PM +0100, Herbert Poetzl wrote: > > So perhaps it should be. If you look at the equivalent topology on > > SAS, our expanders have a bsg device node precisely so that we can do > > this. > > I agree, the PMP should get a device or at least some kind of > interface to address them, especially as the SATA topology can > get quite complicated too, for example it seems that PMPs can > be daisy chained in an infinite sequence like this > > / / / > --[PM]---[PM]---[PM]-- - - > \ \ \ Oh, no, that's not allowed. You can't address destinations that way. PMP is primarily a switch, not a router. > > Sure, as long as it speaks standard ses-2, there shouldn't be a > > protocol problem. The main problem is recognition: ses has to bind > > to an enclosure device. It can bind either to an explicit device > > (about all the enclosures I've seen so far) where the ses device has > > a separate address in the SCSI topology or an implicit device (where > > another SCSI device indicates it has an enclosure port embedded in > > it). As currently coded, our ses driver only does the former probably > > the best way is to expose the ses device via libata and we'll simply > > bind to it. > > so AHCI em_messages use standard ses-2 or did I misinterpret > this (for me cryptical) information? AFAIK, it just doesn't care. It could be ses-2 or whatever else. It just transmits the binary blob it receives via sysfs and vice-versa. Thanks. -- tejun