From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.southpole.se (mail.southpole.se [193.12.106.18]) by ozlabs.org (Postfix) with ESMTP id 8BE2DB7BCC for ; Wed, 28 Oct 2009 20:56:49 +1100 (EST) Subject: RE: Accessing flash directly from User Space From: Kenneth Johansson To: Jonathan Haws In-Reply-To: References: <4AE7545F.80805@billgatliff.com> <4AE75859.5050108@billgatliff.com> <4AE774ED.8050502@freescale.com> <4AE7775D.8080502@freescale.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 28 Oct 2009 10:56:45 +0100 Message-Id: <1256723805.32158.241.camel@kenjo-laptop> Mime-Version: 1.0 Cc: Scott Wood , Bill Gatliff , "linuxppc-dev@lists.ozlabs.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, 2009-10-27 at 16:52 -0600, Jonathan Haws wrote: > > Jonathan Haws wrote: > > > I had thought about using MTD, but decided against it because with > > > previous benchmarking that we did with MTD and our custom driver, > > we > > > found that our custom driver was about 10x faster. > > > > Ouch. Any idea where the slowdown is coming from? > > From what I remember (I would have to dig up notes to make sure) it is something to do with MTD looking for a signal to go high that is processed a bunch before MTD even sees it. Our flash produces a hardware ready signal that we are triggering off of to move on. MTD took much longer to report to us that the hardware was ready. > > Thanks > It would be interesting to know in more detail what is was. If we have a 10x performance increase hiding from for us I would be very interested in knowing where it is. Are you using some custom command to the flash that the generic chip drivers in Linux is not yet supporting ?