From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bear.ext.ti.com ([192.94.94.41]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Wnkf8-00012w-Hf for linux-mtd@lists.infradead.org; Fri, 23 May 2014 08:17:10 +0000 Message-ID: <537F03C8.3070101@ti.com> Date: Fri, 23 May 2014 11:16:08 +0300 From: Roger Quadros MIME-Version: 1.0 To: Ezequiel Garcia , Tony Lindgren , Javier Martinez Canillas Subject: Re: [RFC PATCH 00/16] OMAP: GPMC: Restructure OMAP GPMC driver (NAND) : DT binding change proposal References: <1400671264-10702-1-git-send-email-rogerq@ti.com> <20140521160818.GA1150@arch.cereza> <537DB17A.6060608@ti.com> <20140522144600.GA1785@arch.cereza> In-Reply-To: <20140522144600.GA1785@arch.cereza> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: "devicetree@vger.kernel.org" , "linux-omap@vger.kernel.org" , Robert Nelson , Jingoo Han , nsekhar@ti.com, Linux Kernel , Rob Herring , linux-mtd@lists.infradead.org, "Gupta, Pekon" , Grant Likely , Brian Norris , dwmw2@infradead.org List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Ezequiel & Javier, On 05/22/2014 05:46 PM, Ezequiel Garcia wrote: > On 22 May 01:51 PM, Javier Martinez Canillas wrote: >> On Thu, May 22, 2014 at 10:12 AM, Roger Quadros wrote: >>>> On 21 May 02:20 PM, Roger Quadros wrote: >>>>> >>>>> For DT boot: >>>>> - The GPMC controller node should have a chip select (CS) node for each used >>>>> chip select. The CS node must have a child device node for each device >>>>> attached to that chip select. Properties for that child are GPMC agnostic. >>>>> >>>>> i.e. >>>>> gpmc { >>>>> cs0 { >>>>> nand0 { >>>>> } >>>>> }; >>>>> >>>>> cs1 { >>>>> nor0 { >>>>> } >>>>> } >>>>> ... >>>>> }; >>>>> >>>> >>>> While I agree that the GPMC driver is a bit messy, I'm not sure it's possible >>>> to go through such a complete devicetree binding re-design (breaking backwards >>>> compatibility) now that the binding is already in production. >>> >>> Why not? especially if the existing bindings are poorly dones. Is anyone using these >>> bindings burning the DT into ROM and can't change it when they update the kernel? >>> >> >> While I do agree that your DT bindings are much better than the >> current ones, there is a policy that DT bindings are an external API >> and once are released with a kernel are set in stone and can't be >> changed. >> > > Exactly. The DT binding is considered an ABI. Thus, invariant across kernel > versions. Users can't be coherced into a DTB update after a kernel update. > > That said, I don't really care if you break compatilibity in this case. > Rather, I'm suggesting that you make sure this change is going to be accepted > upstream, before doing any more work. The DT maintainers are reluctant to do > so. Appreciate your concern. Would be really nice if you can review patches 1-12. They have nothing to do with DT changes. Thanks. cheers, -roger > > On the other side, I guess you will also break bisectability while breaking > backward compatibility. Doesn't sound very nice. >