From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from co9outboundpool.messaging.microsoft.com (co9ehsobe001.messaging.microsoft.com [207.46.163.24]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "Microsoft Secure Server Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 5F2C22C0086 for ; Tue, 4 Dec 2012 04:04:32 +1100 (EST) Date: Mon, 3 Dec 2012 11:03:43 -0600 From: Scott Wood Subject: Re: [PATCH 3/4 v5] iommu/fsl: Add iommu domain attributes required by fsl PAMU driver. To: Sethi Varun-B16395 References: <1353419697-31269-1-git-send-email-Varun.Sethi@freescale.com> <1353419697-31269-4-git-send-email-Varun.Sethi@freescale.com> <20121202140323.GO30633@8bytes.org> In-Reply-To: (from B16395@freescale.com on Mon Dec 3 10:57:29 2012) Message-ID: <1354554223.2960.7@snotra> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; delsp=Yes; format=Flowed Cc: Wood Scott-B07421 , Joerg Roedel , Tabi Timur-B04825 , "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "linuxppc-dev@lists.ozlabs.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 12/03/2012 10:57:29 AM, Sethi Varun-B16395 wrote: >=20 >=20 > > -----Original Message----- > > From: iommu-bounces@lists.linux-foundation.org [mailto:iommu- > > bounces@lists.linux-foundation.org] On Behalf Of Joerg Roedel > > Sent: Sunday, December 02, 2012 7:33 PM > > To: Sethi Varun-B16395 > > Cc: linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org; =20 > Wood > > Scott-B07421; linuxppc-dev@lists.ozlabs.org; Tabi Timur-B04825 > > Subject: Re: [PATCH 3/4 v5] iommu/fsl: Add iommu domain attributes > > required by fsl PAMU driver. > > > > Hmm, we need to work out a good abstraction for this. > > > > On Tue, Nov 20, 2012 at 07:24:56PM +0530, Varun Sethi wrote: > > > Added the following domain attributes required by FSL PAMU driver: > > > 1. Subwindows field added to the iommu domain geometry attribute. > > > > Are the Subwindows mapped with full size or do you map only parts =20 > of the > > subwindows? > > > [Sethi Varun-B16395] It's possible to map a part of the subwindow =20 > i.e. size of the mapping can be less than the sub window size. >=20 > > > + * This attribute indicates number of DMA subwindows supported =20 > by > > > + * the geometry. If there is a single window that maps the =20 > entire > > > + * geometry, attribute must be set to "1". A value of "0" =20 > implies > > > + * that this mechanism is not used at all(normal paging is =20 > used). > > > + * Value other than* "0" or "1" indicates the actual number of > > > + * subwindows. > > > + */ > > > > This semantic is ugly, how about a feature detection mechanism? > > > [Sethi Varun-B16395] A feature mechanism to query the type of IOMMU? A feature mechanism to determine whether this subwindow mechanism is =20 available, and what the limits are. -Scott=