From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wa-out-1112.google.com (wa-out-1112.google.com [209.85.146.178]) by ozlabs.org (Postfix) with ESMTP id 73CEADEB09 for ; Fri, 6 Jun 2008 07:38:50 +1000 (EST) Received: by wa-out-1112.google.com with SMTP id n7so487196wag.13 for ; Thu, 05 Jun 2008 14:38:49 -0700 (PDT) Message-ID: <9e4733910806051438g2b0bdd8tc4fbfceecd8dc1ea@mail.gmail.com> Date: Thu, 5 Jun 2008 17:38:48 -0400 From: "Jon Smirl" To: "Sascha Hauer" Subject: Re: jffs2 and unaligned access In-Reply-To: <20080507132514.GF4326@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 References: <20080507102724.GE4326@pengutronix.de> <1210157630.25560.884.camel@pmac.infradead.org> <20080507132514.GF4326@pengutronix.de> Cc: linux-mtd@lists.infradead.org, David Woodhouse , linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 5/7/08, Sascha Hauer wrote: > On Wed, May 07, 2008 at 11:53:49AM +0100, David Woodhouse wrote: > > On Wed, 2008-05-07 at 12:27 +0200, Sascha Hauer wrote: > > > memcpy_from/to_io() use word aligned accesses on the io side of memory. > > > The MPC5200 local plus bus where our flashes are connected does not > > > allow unaligned accesses, so we have to use the io versions of memcpy. > > > > But this region of flash is marked as suitable for execute-in-place, > > otherwise the point() function wouldn't be working to give a direct > > pointer to it. It sounds like we shouldn't be allowing that. > > > It actually is suitable for execute-in-place. It's the flash U-Boot > starts from. The compiler will generate a proper alignment for you. > > > > > > Which in turn means that perhaps we should have a property in the > > corresponding node in the device-tree which indicates that it's not > > suitable for direct access? > > > So far we did not work with the device-tree flash binding but with the > physmap-flash driver, but ok, this is subject to change anyway. > > I gave it a quick try to disable direct accesses. It works, but has a > 1:10 performance impact on mounting a jffs2. At least it's a clean > solution. How did this get resolved? The thread died without any final solution being proposed. > > > Sascha > > > > -- > Pengutronix e.K. - Linux Solutions for Science and Industry > ----------------------------------------------------------- > Kontakt-Informationen finden Sie im Header dieser Mail oder > auf der Webseite -> http://www.pengutronix.de/impressum/ <- > -- Jon Smirl jonsmirl@gmail.com