From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH] SCSI midlayer power management Date: 12 Aug 2004 15:34:02 -0400 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <1092339247.1755.36.camel@mulgrave> 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> <20040812131457.GB1086@elf.ucw.cz> <1092328173.2184.15.camel@mulgrave> <20040812191120.GA14903@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from stat16.steeleye.com ([209.192.50.48]:62436 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S268676AbUHLTea (ORCPT ); Thu, 12 Aug 2004 15:34:30 -0400 In-Reply-To: <20040812191120.GA14903@elf.ucw.cz> List-Id: linux-scsi@vger.kernel.org To: Pavel Machek Cc: Benjamin Herrenschmidt , Nathan Bryant , Linux SCSI Reflector , Linux Kernel list , Jeff Garzik On Thu, 2004-08-12 at 15:11, Pavel Machek wrote: > Ok, but what happens on next resume? If coherent mbox is at exactly > same place at every boot I guess it could even work, but... Er, well this is a huge problem then. Even if DMA were stopped, the registers for all these locations need to be altered to change the location of the DMA mboxes. This isn't just a SCSI problem, it's a general device problem (most devices having mboxes programmed by register). If we can't rely on the resuming kernel setting up these registers for us to exactly what they were in the resume image, then we're in a bit of trouble. Architecturally what you are trying to do is to re POST the SCSI card. Except it's the kernel's job to POST it, so the kernel init code needs to be re-run. I assume that's what the pci suspend/resume calls are supposed to do? James