From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from imap.sh.mvista.com (unknown [63.81.120.155]) by ozlabs.org (Postfix) with ESMTP id 5E9BFDDE27 for ; Mon, 4 Jun 2007 04:01:31 +1000 (EST) Message-ID: <46630256.8050909@ru.mvista.com> Date: Sun, 03 Jun 2007 22:03:02 +0400 From: Sergei Shtylyov MIME-Version: 1.0 To: Segher Boessenkool Subject: Re: [PATCH] powerpc: Create "rom" (MTD) device prpmc2800 References: <7fc919fce0761f861be3069a853d3169@bga.com> <1180769992.14025.1.camel@localhost.localdomain> <4662E7EA.70506@ru.mvista.com> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Cc: ppcdev , linux-mtd@lists.infradead.org, Milton Miller List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hello. Segher Boessenkool wrote: >>> If it's a flash, compatible should be the chip type, and maybe as a >>> second entry, what type of flash protocol (amd, intel, cfi, ...) it's >>> compatible. >> As I've already (and repatedly) stated before, > And you repeatedly got answers too, yet you choose > to rehash this whole discussion again. Not I have started it. And I have my reasons, too. :-) >> this gets you *nothing* WRT >> selecting the proper driver in the current Linux MTD subsystem. > Which Linux driver to use is not something that should > be (directly) communicated in a device tree -- even if Bah... what's "name" and "compatible" properties are for then. Nobody's talking about the direct match but making the task of selecting a proper driver more complex by specifying the details that don't help (if not hinder) the correct selection is certainly not a way to go. > you take the position the device tree is a nice big > configuration file for Linux, what if a new Linux flash > subsystem shows up (or even simply a driver got renamed, > etc.) There is no direct match in *this* case (for an example of such, refer to FSL "gianfar" nodes ;-). > -- the device tree on your board doesn't necessarily > change when your kernel version does. Well, I'm not anticipating any changes either in this case... >> What it >> actually *needs* to know is flash mapping information, > It needs to know what kind of flash it is, and how it > is connected -- i.e., it needs to describe the hardware. > How Linux then decides to use it is its own game, but > at least the device tree puts all the information it > could possibly need out there. >> the CFI/JEDEC interface then can be deduced by probing > Most of the time, sure. Not always. That's the way the cookie crumbles in Linux MTD for now. It's *always* detecting this by probing -- you only can say what [not] to probe. >> -- so, this property ("ptobe-type"), although specified in >> Documentation/powerpc/booting-without-of.txt, is optional. > Who is talking about "probe-type"? We are talking about "compatible". See my other mail where I've told why I don't consider your example of this prop valid... > Segher WBR, Sergei