From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-in-07.arcor-online.net (mail-in-07.arcor-online.net [151.189.21.47]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx.arcor.de", Issuer "Thawte Premium Server CA" (verified OK)) by ozlabs.org (Postfix) with ESMTP id B0061DDF11 for ; Fri, 8 Jun 2007 02:46:51 +1000 (EST) In-Reply-To: <1181232358.2785.79.camel@pmac.infradead.org> References: <7fc919fce0761f861be3069a853d3169@bga.com> <4662EAA9.70104@ru.mvista.com> <466308F4.8050004@ru.mvista.com> <8ac5664208e0f59329b62ac2138bbc8c@kernel.crashing.org> <466312C2.4090200@ru.mvista.com> <548a7e11ffb577f6395b8f5a9c2fba2d@kernel.crashing.org> <466323EF.5040807@ru.mvista.com> <1181228442.2785.60.camel@pmac.infradead.org> <18fbfbaf113ab76b602d279848d9b405@kernel.crashing.org> <1181232358.2785.79.camel@pmac.infradead.org> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <04823a3fa3fc5d1e6c14ef896fabfdb0@kernel.crashing.org> From: Segher Boessenkool Subject: Re: [PATCH] powerpc: Create "rom" (MTD) device prpmc2800 Date: Thu, 7 Jun 2007 18:46:45 +0200 To: David Woodhouse Cc: linuxppc-dev@ozlabs.org, 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: , >> So I think the best thing to have would be >> >> compatible "cfi-flash" >> bank-width like you said >> device-width width of a single flash device >> reg complete address range of this thing >> >> and then the Linux OF CFI flash code / MTD code just keeps >> on probing devices from that address range until it has it >> filled. >> >> Sounds good / comments / anything I missed? > > That seems reasonable. I would personally have used 'interleave' to > give > the number of devices interleaved together into the specified > bank-width, rather than specifying device-width. I think "device-width" is much clearer -- from the name "interleave" you cannot tell that it actually means "number-of-interleaved-devices-in-this-bank". > People might get > confused by device-width because many devices can actually be _either_ > x16 or x8. Well after it has been soldered down to the board, it's pretty much fixed what the device's bus width is ;-) > But I don't care much. Linux will only be using the > bank-width anyway. So it can reliably detect interleaving itself? I'd like "device-width" to be a required property still, for the benefit of non-Linux device tree users, or just in case. > The other thing that might be seen in the 'compatible' property would > be > 'jedec-flash', I don't want to deal with that yet, one thing at a time, and CFI flash it is now. JEDEC is a bit hairier. > and in that case perhaps we also want properties for the > manufacturer and device ident? Certainly, since they cannot be reliably probed. > Linux wouldn't necessarily care about > them, but other operating systems might. > > And we also need partition information to get through somehow, in the > cases where the firmware knows it. A child node per partition I suppose, dunno. Segher