From mboxrd@z Thu Jan 1 00:00:00 1970 From: geert@linux-m68k.org (Geert Uytterhoeven) Date: Wed, 23 May 2018 08:25:24 +0200 Subject: [PATCH 6/9] ARM: dts: wheat: Drop MTD partitioning from DT In-Reply-To: References: <20180522120257.13232-1-marek.vasut+renesas@gmail.com> <20180522120257.13232-6-marek.vasut+renesas@gmail.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Marek, 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 at 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. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert at linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds