From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-out.m-online.net (mail-out.m-online.net [212.18.0.9]) by ozlabs.org (Postfix) with ESMTP id 84A40DDF2F for ; Thu, 26 Apr 2007 22:56:29 +1000 (EST) Message-ID: <4630A243.8020404@grandegger.com> Date: Thu, 26 Apr 2007 14:59:47 +0200 From: Wolfgang Grandegger MIME-Version: 1.0 To: Sergei Shtylyov Subject: Re: Flat device tree definitions for FLASH and MTD partitioning References: <4618D400.8050003@grandegger.com> <4618DBEF.30307@ru.mvista.com> <4618DE4A.4020404@ru.mvista.com> <462F4FD1.6080900@grandegger.com> <462F592F.7000409@ru.mvista.com> <462F5F86.3060309@grandegger.com> <462F6707.80502@ru.mvista.com> <4630611C.4060902@grandegger.com> <46309CD9.1050403@ru.mvista.com> In-Reply-To: <46309CD9.1050403@ru.mvista.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sergei Shtylyov wrote: > Hello. > > Wolfgang Grandegger wrote: > >>>>>>>>> are there already some thought or even example code on how to >>>>>>>>> define Flash memory and MTD partitions in the DTS. This would >>>>>>>>> avoid the ackward MTD partitioning via static structure or boot >>>>>>>>> line argument and could be done in a generic way. > >>>>>>>> See Documentation/powerpc/booting-without-of.txt and >>>>>>>> drivers/mtd/physmap_of.c for what's been already done. > >>>>>>> I meant drivers/mtd/maps/physmap_of.c > >>>>>> I had a closer look to this driver. Unfortunately, it can not >>>>>> handle yet multiple FLASH banks. This could be achieved with an >>>>>> additional property "bank_count". What do you think? > >>> Please use hyphen, not underscore in property names ("device_type" >>> seems an only exception from this rule). > >> Yes, I know and I also wondered why an "_" is used for the device type. > > Ask the OF spec. developers. :-) > >>>>> I'm not sure what banks you're talking about -- note that this >>>>> driver is equivalen in functionality to the plain 'physmap' driver >>>>> and there's inherited "bank-width" property that handles flash >>>>> banking. > >>>> Yes, I know. Nevertheless the driver cannot handle flash regions >>>> composed of more than on FLASH bank because we need to probe every >>>> bank. Search for "BANK" in drivers/mtd/maps" to understand what I mean. > >>> Hm, from what I could see, those banks are separate maps registered >>> to MTD subsys separately. >>> What's the point of adding a count property when we simply can define >>> multiple "rom" devices? > >> To complete this thread, physmap_of can map _one_ FLASH region >> composed of one or more FLASH banks. But it currently cannot map more >> than _one_ FLASH region. > > I wodner why?! :-O I know as well ;-). >> It would be nice to extend it for multiple FLASH definitions (could >> code it when time permits). > > I'm seeing nothing that prevents it from working now -- it should > register as much "rom" devices as you supply via the device tree. OK, I see, for each registered direct-mapped flash resource, of_physmap_probe() will be called. Thanks. Wolfgang.