From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Hunter Subject: Re: [PATCH v7 5/5] ARM: OMAP: gpmc: add DT bindings for GPMC timings and NAND Date: Thu, 6 Dec 2012 12:11:02 -0600 Message-ID: <50C0DFB6.9060501@ti.com> References: <1354734571-10774-1-git-send-email-zonque@gmail.com> <1354734571-10774-6-git-send-email-zonque@gmail.com> <20121205222232.67B2B3E0E22@localhost> <50BFCBCC.6030706@ti.com> <20121205232426.BAD573E0E22@localhost> <20121206000302.GM21682@atomide.com> <50C0C646.9000802@ti.com> <50C0CDB0.5050008@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <50C0CDB0.5050008-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: Daniel Mack Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, nsekhar-l0cyMroinI0@public.gmane.org, rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org, x0148406-l0cyMroinI0@public.gmane.org, linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: linux-omap@vger.kernel.org On 12/06/2012 10:54 AM, Daniel Mack wrote: > On 06.12.2012 17:22, Jon Hunter wrote: >> >> On 12/05/2012 06:03 PM, Tony Lindgren wrote: >>> * Grant Likely [121205 15:26]: >>>> On Wed, 5 Dec 2012 16:33:48 -0600, Jon Hunter wrote: >>>>> On 12/05/2012 04:22 PM, Grant Likely wrote: >>>>>> >>>>>> Please, be specific. Use something like "ti,am3340-gpmc" or >>>>>> "ti,omap3430-gpmc". The compatible property is a list so that new >>>>>> devices can claim compatibility with old. Compatible strings that are >>>>>> overly generic are a pet-peave of mine. >>>>> >>>>> We aim to use the binding for omap2,3,4,5 as well as the am33xx devices >>>>> (which are omap based). Would it be sufficient to have "ti,omap2-gpmc" >>>>> implying all omap2+ based devices or should we have a compatible string >>>>> for each device supported? >>>> >>>> Are they each register-level compatible with one another? >>>> >>>> The general recommended approach here is to make subsequent silicon >>>> claim compatibility with the first compatible implementation. >>>> >>>> So, for an am3358 board: >>>> compatible = "ti,am3358-gpmc", "ti,omap2420-gpmc"; >>>> >>>> Essentially, what this means is that "ti,omap2420-gpmc" is the generic >>>> value instead of "omap2-gpmc". The reason for this is so that the value >>>> is anchored against a specific implementation, and not against something >>>> completely imaginary or idealized. If a newer version isn't quite >>>> compatible with the omap2420-gpmc, then it can drop the compatible claim >>>> and the driver really should be told about the new device. >>> >>> The compatible property can also be used to figure out which ones >>> need the workarounds in patch #4 of this series for the DT case. >>> So we should be specific with the compatible. >> >> We should not merged patch #4. Daniel included this here because he is >> using this on the current mainline, however, this is not needed for >> linux-next and so we should drop it. > > I think we're talking about different things here since awhile. > > The patch I pointed you which is in mainline and which removes the > reference to from drivers/mtd/nand/omap2.c has nothing to > do with my patch #4. It just solves Tony's concern that regarding the > multi-arch zImages. > > My code in gpmc.c calls gpmc_nand_init() which in turn calls > gpmc_hwecc_bch_capable(). Without path #4, gpmc_hwecc_bch_capable() will > return 0, and the nand init will fail consequently, in mainline as well > as in linux-next. Ok, yes I see that now. I should have looked more closely at linux-next. > I understood Tony that he wanted to remove the entiry function and do > the check based on DT properties, which will then solve the problem on a > different level. However, that change is planned for *after* the merge > window. Well now that it is only being called from within the platform code and not from drivers, it is ok. Cheers Jon