From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH v2 1/2] omap3: iovmm: Work around sg_alloc_table size limitation in IOMMU Date: Wed, 1 Jun 2011 06:11:44 -0700 Message-ID: <20110601131144.GG11352@atomide.com> References: <20110531132233.GQ11352@atomide.com> <1306931102-10943-1-git-send-email-laurent.pinchart@ideasonboard.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mho-04-ewr.mailhop.org ([204.13.248.74]:37390 "EHLO mho-02-ewr.mailhop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750753Ab1FANLq (ORCPT ); Wed, 1 Jun 2011 09:11:46 -0400 Content-Disposition: inline In-Reply-To: <1306931102-10943-1-git-send-email-laurent.pinchart@ideasonboard.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Laurent Pinchart Cc: linux-omap@vger.kernel.org * Laurent Pinchart [110601 05:21]: > sg_alloc_table can only allocate multi-page scatter-gather list tables > if the architecture supports scatter-gather lists chaining. ARM doesn't > fit in that category. > > The IOMMU driver abuses the sg table structure only to hold page > addresses without ever passing the table to the device. > > Use __sg_alloc_table instead of sg_alloc_table and allocate all entries > in one go. Otherwise trying to use a large userspace to capture video > will hit a BUG_ON in __sg_alloc_table. Is the "large userspace" above missing a word like buffer? Tony