On 16 November 2012 18:28, Tomasz Figa <t.f...@samsung.com> wrote: > On Friday 16 of November 2012 18:03:15 Thomas Abraham wrote: >> On 16 November 2012 16:41, Tomasz Figa <t.f...@samsung.com> wrote: >> > On Thursday 15 of November 2012 13:48:55 Thomas Abraham wrote: >> >> Hi Tomasz, >> >> >> >> Thanks for your comments. >> >> >> >> On 12 November 2012 19:37, Tomasz Figa <t.f...@samsung.com> wrote: >> >> > Hi Thomas, >> >> > >> >> > On Saturday 03 of November 2012 20:19:32 Thomas Abraham wrote: >> >> >> Add a minimal board dts file for Samsung Exynos4412 based SMDK >> >> >> board. >> >> >> >> >> >> Signed-off-by: Thomas Abraham <thomas.abra...@linaro.org> >> >> >> --- >> >> >> This patch depends the on the following patch posted by Tomasz >> >> >> Figa. >> >> >> "ARM: dts: exynos4: Add support for Exynos4x12 SoCs" >> >> >> >> >> >> arch/arm/boot/dts/Makefile | 1 + >> >> >> arch/arm/boot/dts/exynos4412-smdk4412.dts | 45 >> >> >> >> >> >> +++++++++++++++++++++++++++++ 2 files changed, 46 insertions(+), 0 >> >> >> deletions(-) >> >> >> >> >> >> create mode 100644 arch/arm/boot/dts/exynos4412-smdk4412.dts >> >> >> >> >> >> diff --git a/arch/arm/boot/dts/Makefile >> >> >> b/arch/arm/boot/dts/Makefile >> >> >> index f37cf9f..36488a5 100644 >> >> >> --- a/arch/arm/boot/dts/Makefile >> >> >> +++ b/arch/arm/boot/dts/Makefile >> >> >> @@ -23,6 +23,7 @@ dtb-$(CONFIG_ARCH_DOVE) += dove-cm-a510.dtb \ >> >> >> >> >> >> dtb-$(CONFIG_ARCH_EXYNOS) += exynos4210-origen.dtb \ >> >> >> >> >> >> exynos4210-smdkv310.dtb \ >> >> >> exynos4210-trats.dtb \ >> >> >> >> >> >> + exynos4412-smdk4412.dtb \ >> >> >> >> >> >> exynos5250-smdk5250.dtb >> >> >> >> >> >> dtb-$(CONFIG_ARCH_HIGHBANK) += highbank.dtb >> >> >> dtb-$(CONFIG_ARCH_INTEGRATOR) += integratorap.dtb \ >> >> >> >> >> >> diff --git a/arch/arm/boot/dts/exynos4412-smdk4412.dts >> >> >> b/arch/arm/boot/dts/exynos4412-smdk4412.dts new file mode 100644 >> >> >> index 0000000..f05bf57 >> >> >> --- /dev/null >> >> >> +++ b/arch/arm/boot/dts/exynos4412-smdk4412.dts >> >> >> @@ -0,0 +1,45 @@ >> >> >> +/* >> >> >> + * Samsung's Exynos4412 based SMDK board device tree source >> >> >> + * >> >> >> + * Copyright (c) 2012-2013 Samsung Electronics Co., Ltd. >> >> >> + * http://www.samsung.com >> >> >> + * >> >> >> + * Device tree source file for Samsung's SMDK4412 board which is >> >> >> based >> >> >> on + * Samsung's Exynos4412 SoC. >> >> >> + * >> >> >> + * This program is free software; you can redistribute it and/or >> >> >> modify + * it under the terms of the GNU General Public License >> >> >> version 2 as + * published by the Free Software Foundation. >> >> >> +*/ >> >> >> + >> >> >> +/dts-v1/; >> >> >> +/include/ "exynos4412.dtsi" >> >> >> + >> >> >> +/ { >> >> >> + model = "Samsung SMDK evaluation board based on Exynos4412"; >> >> >> + compatible = "samsung,smdk4412", "samsung,exynos4412"; >> >> >> + >> >> >> + memory { >> >> >> + reg = <0x40000000 0x40000000>; >> >> >> + }; >> >> > >> >> > This will not boot, because section size limit is set to 256 MiB. >> >> > >> >> > It might work with CONFIG_ARM_ATAG_DTB_COMPAT enabled, because the >> >> > memory configuration from DT is ignored and values from ATAGs are >> >> > taken instead. >> >> > >> >> > I suggest you to change it to 4 banks of 256 MiB. >> >> >> >> Thanks for pointing this out. So are there any existing exynos based >> >> platforms that use sparse mem? If not, we should probably remove the >> >> section length configuration itself for mach-exynos. I suspect this >> >> setting might not help with the single kernel image support as well. >> > >> > Isn't sparse memory the only configuration available for ARCH_EXYNOS? >> >> Yes, true. Since sparsemem is choosen as default for Exynos, flatmem >> option is not available. Theoretically, sparsemem could be used on >> Exynos platforms, but if all existing exynos4/5 based boards have no >> holes in memory, then why not use flatmem instead? If there are >> performance benefits of using flatmem over sparesmem on systems >> without any memory holes, then it is a compelling reason to stop using >> sparsemem on Exynos. But then, what if there is a new Exynos4/5 based >> board that comes up and that has a memory hole? Or, how about removing >> sparsemem as default option for ARCH_EXYNOS and enabling sparsemem for >> boards that need it. > > I'm not sure about any significant performance benefits of FLATMEM over > SPARSEMEM. Some ancient benchmark from 2007 shows that overhead level of > both is similar. > > You can find the benchmark here: > http://lkml.indiana.edu/hypermail/linux/kernel/0711.1/1239.html > > I think we should leave it as is for the time being and just make sure > that sections of boards are defined according to section size limit.
Ok, makes sense. Thanks. By the way, I was checking why this patch did not lead me to a crash as you described. u-boot seems to be overriding the memory node in the dts file and creating a new memory node with the memory banks information that u-boot has. So looking at /proc/device-tree/memory/reg, there are multiple 256MB sized entries there. Regards, Thomas. _______________________________________________ devicetree-discuss mailing list devicetree-discuss@lists.ozlabs.org https://lists.ozlabs.org/listinfo/devicetree-discuss
