From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Subject: Should isci create its own device class? Date: Tue, 01 Mar 2011 19:22:39 -0800 Message-ID: <4D6DB7FF.4090506@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mga03.intel.com ([143.182.124.21]:30423 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757722Ab1CBDWk (ORCPT ); Tue, 1 Mar 2011 22:22:40 -0500 Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Greg KH , James Bottomley , Kay Sievers Cc: "linux-scsi@vger.kernel.org" , "Nadolski, Edmund" , "Jiang, Dave" , "Skirvin, Jeffrey D" , "Danecki, Jacek" For compatibility with other software raid environments an isci [1] device may contain up to two controller instances per pci device. Currently the sysfs path for its scsi_host objects is: > ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:08.0/0000:03:00.0/host10/scsi_host/host10 > ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:08.0/0000:03:00.0/host11/scsi_host/host11 But to reflect reality the pci device is actually the parent of two independent controller instances. With a mockup like: > ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:08.0/0000:03:00.0/controller0/host10/scsi_host/host10 > ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/0000:02:08.0/0000:03:00.0/controller1/host11/scsi_host/host11 I can see this being beneficial in a few ways: 1/ fix dev_printk() messages which right now give an ambiguous "isci 0000:03:00.0" prefix 2/ controller boundaries are visible via the sysfs path without need to to look at sas_addresses to determine the controller. 2/ if we ever wanted to support some per controller attributes between the global pci attributes and the scsi_host attributes. ...but would this confuse /dev/disk/by-path/ or any other unintended side effects? -- Dan [1]: http://marc.info/?l=linux-scsi&m=129703780424729&w=2