From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kristen Carlson Accardi Subject: Re: AHCI link power management and surprise hotplug Date: Fri, 20 Mar 2009 10:42:57 -0700 Message-ID: <20090320104257.5cf1e7cc@appleyard> References: <49C22689.9050005@buttersideup.com> Reply-To: kristen.c.accardi@intel.com Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com ([192.55.52.93]:50177 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753146AbZCTRma (ORCPT ); Fri, 20 Mar 2009 13:42:30 -0400 In-Reply-To: <49C22689.9050005@buttersideup.com> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Tim Small Cc: "linux-ide@vger.kernel.org" On Thu, 19 Mar 2009 04:03:37 -0700 Tim Small wrote: > Hello, > > I've been configuring SATA link power management > (Documentation/scsi/link_power_management_policy.txt) on servers which > use software RAID for a while, but I happened to come across this in the > ICH9 datasheet: > > " > For reliable device removal notification while in AHCI operation without > the use of interlock switches (surprise removal), interface power > management should be disabled for the associated port. See Section 7.3.1 > of the AHCI Specification for more information. > " > > > Is this actually an issue from a libata point of view? Do I need to > ensure that link power management is disabled prior to hot-removal, and > if so, I suppose link_power_management_policy.txt should be updated to > reflect this... Hi, Yes - this is an issue. Right now we disable hotplug when link power management is enabled because when your link is in a lower power state it cannot detect the phy state changes. Most platforms I've seen do not support the interlock switches - so ATM link pwr management and hotplug are mutually excludive. I agree that the documentation should reflect this - would you like to submit a patch to the link_power_management_policy.txt file? Thanks! Kristen