From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 41AB56B0055 for ; Thu, 25 Jun 2009 14:50:20 -0400 (EDT) Date: Fri, 26 Jun 2009 03:50:47 +0900 From: Paul Mundt Subject: Re: [PATCH] video: arch specific page protection support for deferred io Message-ID: <20090625185047.GA25916@linux-sh.org> References: <20090624105413.13925.65192.sendpatchset@rx1.opensource.se> <20090624195647.9d0064c7.akpm@linux-foundation.org> <20090625000359.7e201c58.akpm@linux-foundation.org> <20090625173806.GB25320@linux-sh.org> <20090625111233.f6f26050.akpm@linux-foundation.org> <45a44e480906251136l3a83188bm3f730534f89d00cb@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45a44e480906251136l3a83188bm3f730534f89d00cb@mail.gmail.com> Sender: owner-linux-mm@kvack.org To: Jaya Kumar Cc: Andrew Morton , magnus.damm@gmail.com, linux-fbdev-devel@lists.sourceforge.net, adaplas@gmail.com, arnd@arndb.de, linux-mm@kvack.org List-ID: On Fri, Jun 26, 2009 at 02:36:23AM +0800, Jaya Kumar wrote: > On Fri, Jun 26, 2009 at 2:12 AM, Andrew Morton wrote: > > On Fri, 26 Jun 2009 02:38:06 +0900 > > Paul Mundt wrote: > > > >> On Thu, Jun 25, 2009 at 12:03:59AM -0700, Andrew Morton wrote: > >> > On Thu, 25 Jun 2009 15:06:24 +0900 Magnus Damm wrote: > >> > > There are 3 levels of dependencies: > >> > > 1: pgprot_noncached() patches from Arnd > >> > > 2: mm: uncached vma support with writenotify > >> > > 3: video: arch specfic page protection support for deferred io > >> > > > >> > > 2 depends on 1 to compile, but 3 (this one) is disconnected from 2 and > >> > > 1. So this patch can be merged independently. > > > > > > I don't really understand that one. ?Have we heard fro Jaya recently? > > > > He's been having some personal problems so he's been quiet. :-) > > Magnus's defio changes, #3 look fine to me. I don't know much about #2 > but what I understood was that the previous mmap_region code was > unintentionally turning caching back on when it did the writenotify > test and I guess Magnus's goal with the patch is to make sure that > address range is left uncached since sh_mobile uses DMA to transfer > the framebuffer and he might have encountered coherency issues there? > Correct. This could have been documented a bit better, but yes, the issue is that when the writenotify test kicks in the vma silently loses its uncachedness which leads to the aforementioned runtime behaviour issues. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org