From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [PATCH] SCSI midlayer power management Date: Fri, 13 Aug 2004 09:02:17 +1000 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <1092351736.26430.12.camel@gaston> References: <4119611D.60401@optonline.net> <20040811080935.GA26098@elf.ucw.cz> <411A1B72.1010302@optonline.net> <1092231462.2087.3.camel@mulgrave> <1092267400.2136.24.camel@gaston> <1092314892.1755.5.camel@mulgrave> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from gate.crashing.org ([63.228.1.57]:4078 "EHLO gate.crashing.org") by vger.kernel.org with ESMTP id S268854AbUHLXHj (ORCPT ); Thu, 12 Aug 2004 19:07:39 -0400 In-Reply-To: <1092314892.1755.5.camel@mulgrave> List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Nathan Bryant , Pavel Machek , Linux SCSI Reflector , Linux Kernel list , Jeff Garzik On Thu, 2004-08-12 at 22:48, James Bottomley wrote: > On Wed, 2004-08-11 at 19:36, Benjamin Herrenschmidt wrote: > > Some hosts will continuously DMA to memory iirc.. I remember having a > > problem with 53c8xx on some macs when transitionning from MacOS to Linux > > because of that. > > I think you're thinking of the scripts engine? on pre 53c875 chips, > yes, this is true. The on-board processor is executing instructions > from host memory. However, this is read only in quiescent (waiting for > host connect or target reconnect) mode, so shouldn't be a problem for > suspend. On the 875 and later, we host the scripts in on-chip memory so > they shouldn't be troubling main memory when idling. The problem was a 875, the script was writing some kind of status or whatever at regular interval to host memory. Might be specific to the script used by the MacOS driver tho... Ben.