From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH 6/9] ARM: dts: wheat: Drop MTD partitioning from DT To: Simon Horman , Geert Uytterhoeven Cc: Linux ARM , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Marek Vasut , Geert Uytterhoeven , Laurent Pinchart , Wolfram Sang , Linux-Renesas , Richard Weinberger , Boris Brezillon References: <20180522120257.13232-1-marek.vasut+renesas@gmail.com> <20180522120257.13232-6-marek.vasut+renesas@gmail.com> <7e1563c3-3e13-235b-3071-c3936502530f@gmail.com> <20180528084135.q5xng5eaypprsypr@verge.net.au> <20180528093602.eb36j34bbfzmpmw2@verge.net.au> From: Marek Vasut Message-ID: Date: Wed, 30 May 2018 12:13:31 +0200 MIME-Version: 1.0 In-Reply-To: <20180528093602.eb36j34bbfzmpmw2@verge.net.au> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: devicetree-owner@vger.kernel.org List-ID: On 05/28/2018 11:36 AM, Simon Horman wrote: > On Mon, May 28, 2018 at 10:54:57AM +0200, Geert Uytterhoeven wrote: >> Hi Simon, >> >> On Mon, May 28, 2018 at 10:41 AM, Simon Horman wrote: >>> On Thu, May 24, 2018 at 04:52:59PM +0200, Marek Vasut wrote: >>>> On 05/23/2018 08:25 AM, Geert Uytterhoeven wrote: >>>>> On Wed, May 23, 2018 at 12:01 AM, Marek Vasut wrote: >>>>>> On 05/22/2018 04:43 PM, Geert Uytterhoeven wrote: >>>>>>> On Tue, May 22, 2018 at 2:02 PM, Marek Vasut wrote: >>>>>>>> Drop the MTD partitioning from DT, since it does not describe HW >>>>>>>> and to give way to a more flexible kernel command line partition >>>>>>>> passing. >>>>>>>> >>>>>>>> To retain the original partitioning, assure you have enabled >>>>>>>> CONFIG_MTD_CMDLINE_PARTS in your kernel config and add the >>>>>>>> following to your kernel command line: >>>>>>>> >>>>>>>> mtdparts=spi0.0:256k@0(loader),4096k(user),-(flash) >>>>>>> >>>>>>> I think the "@0" can be dropped, as it's optional? >>>>>>> 4m? >>>>>> >>>>>> My take on this is that the loader is actually at offset 0x0 of the MTD >>>>>> device and we explicitly state that in the mtdparts to anchor the first >>>>>> partition within the MTD device and all the other partitions are at >>>>>> offset +(sum of the sizes of all partitions listed before the current >>>>>> one) relative to that first partition. >>>>> >>>>> Where is this explicitly states for the first partition? >>>>> >>>>>> Removing the @0 feels fragile at best and it seems to depend on the >>>>>> current behavior of the code. >>>>> >>>>> Better, it also depends on the documented behavior: >>>>> >>>>> Documentation/admin-guide/kernel-parameters.txt refers to >>>>> drivers/mtd/cmdlinepart.c, which states: >>>>> >>>>> * := standard linux memsize >>>>> * if omitted the part will immediately follow the previous part >>>>> * or 0 if the first part >>>>> >>>>> None of the examples listed there or under the MTD_CMDLINE_PARTS Kconfig >>>>> help text, or in a defconfig bundled with the kernel, use @0 for the first >>>>> partition. >>>> >>>> I think this is exceptionally fragile and dangerous to depend on this, >>>> but so be it. >>> >>> Could you respin with this change? >>> >>> I would also like to ask for another change, in light of recent >>> feedback from Olof Johansson ("Re: [GIT PULL] Renesas ARM64 Based SoC DT >>> Updates for v4.18"). >>> >>> Please consolidate the dts patches into a single patch? >> >> I think it's better to keep them split, as each commit description mentions >> what needs to be passed on the kernel command line for the corresponding >> board. >> >> Combining it in a single patch makes it much harder to extract this information. >> Unless you're fine with a list: >> >> koelsch: ... >> wheat: mtdparts=spi0.0:256k@0(loader),4096k(user),-(flash) > > Lets try a list. Reposted with a list, twice :/ -- Best regards, Marek Vasut