Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757028AbZCFVza (ORCPT ); Fri, 6 Mar 2009 16:55:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753984AbZCFVzT (ORCPT ); Fri, 6 Mar 2009 16:55:19 -0500 Received: from smtp-out.google.com ([216.239.45.13]:41846 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751064AbZCFVzR convert rfc822-to-8bit (ORCPT ); Fri, 6 Mar 2009 16:55:17 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:content-transfer-encoding:x-system-of-record; b=iP/yCInyWNiD9upeAEnYsBCpkO9NT0A1EMGw6zG36tpn5NDGXvcxvlZn2vdNfiDjJ 6J/k4SyFBddj+2Nias6Ow== MIME-Version: 1.0 In-Reply-To: <20090306211832.GV15340@beardog.cca.cpqcorp.net> References: <20090306085529.GP11787@kernel.dk> <20090306181302X.fujita.tomonori@lab.ntt.co.jp> <20090306092114.GS11787@kernel.dk> <20090306182705P.fujita.tomonori@lab.ntt.co.jp> <20090306093520.GV11787@kernel.dk> <20090306143856.GT15340@beardog.cca.cpqcorp.net> <20090306211832.GV15340@beardog.cca.cpqcorp.net> Date: Fri, 6 Mar 2009 13:55:13 -0800 Message-ID: Subject: Re: [PATCH] hpsa: SCSI driver for HP Smart Array controllers From: Grant Grundler To: scameron@beardog.cca.cpqcorp.net Cc: Jens Axboe , FUJITA Tomonori , linux-kernel@vger.kernel.org, mike.miller@hp.com, akpm@linux-foundation.org, linux-scsi@vger.kernel.org, coldwell@redhat.com, hare@novell.com, iss_storagedev@hp.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1701 Lines: 42 On Fri, Mar 6, 2009 at 1:18 PM, wrote: > On Fri, Mar 06, 2009 at 12:59:48PM -0800, Grant Grundler wrote: >> On Fri, Mar 6, 2009 at 6:38 AM,   wrote: >> ... >> > The command buffers have to be in the first 4GB of memory, as the command >> > register is only 32 bits, so they are allocated by pci_alloc_consistent. >> >> Huh?!! >> ISTR the mpt2sas driver is indicating it can handle 64-bit DMA masks for >> both streaming and control data. I need to double check to be sure of that. > > it is something specific to smart array.  The command register that we > stuff the bus address of the command into is only 32 bits wide.  Everything > else it does is 64 bits. Sorry...I'm spacing out and confusing my drivers. thanks, grant >> >> > However, the chained SG lists don't have that limitation, so I think they >> > can be kmalloc'ed, and so not chew up and unreasonable amount of the >> > pci_alloc_consistent memory and get a larger number of SGs.   ...right? >> > Maybe that's the better way to do it. >> >> I thought the driver was tracking this and using the appropriate construct >> based on which DMA mask is in effect. > > The DMA mask is insufficiently expressive to describe the limitations and > capabilities of the Smart array.  There's no way to describe with a single > DMA mask that the command register is 32-bits, but everything else is 64 > bits. > > -- steve > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/