Subject: Re: [RFT PATCH] ARM64: dts: meson-gxbb: Add reserved memory zone and
 usable memory range
To: Neil Armstrong <narmstrong@baylibre.com>, khilman@baylibre.com
References: <20161212101801.28491-1-narmstrong@baylibre.com>
 <09bb78ed-c8ec-d21f-d464-16e55c481d4e@gmx.de>
 <56869b90-6bee-f6ae-a7b1-884b4c0d72c0@baylibre.com>
Cc: carlo@caione.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org
From: Heinrich Schuchardt <xypron.glpk@gmx.de>
Message-ID: <2ac01237-a7f8-5b3b-0f97-dd49ce6623fb@gmx.de>
Date: Thu, 22 Dec 2016 11:02:10 +0100
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On 12/14/2016 10:52 AM, Neil Armstrong wrote:

> Hi Heinrich,
> 
> Thanks for testing and for the report,
> we are still struggling into finding what are these zones and how to label them correctly.
> 
> We need to identify the zones on all boards, the patch I provided works on a non-odroid-c2 and gxm and gxl boards.
> 
> Neil
> 
Hello Neil,

the configuration below works for me on the Hardkernel Odroid C2.

ramoops is needed for CONFIG_PSTORE_RAM.
Debian Stretch has CONFIG_PSTORE_RAM=m. Same is true for Fedora.
I have chosen the address arbitrarily. To accommodate 512 MB boards we
would have to put it below 0x20000000.
The size parameters are the same as in hisilicon/hi6220-hikey.dts and
qcom-apq8064-asus-nexus7-flo.dts.

linux,cma is used for contiguous memory assignment. I have taken the
align parameter from arm-src-kernel-2016-08-18-26e194264c.tar.gz
provided by Amlogic at
http://openlinux.amlogic.com:8000/download/ARM/kernel/ .
See Documentation/DMA-API.txt for the usage of align.
They use the same value 0x400000 for all GXBB boards.
So we want to put this zone into meson-gxbb.dtsi.

secmon is used by drivers/firmware/meson/meson_sm.c.
Amlogic uses the same address range for all 64bit boards.

	memory@0 {
		device_type = "memory";
		linux,usable-memory = <0x0 0x1000000 0x0 0x7f000000>;
	};

	reserved-memory {
		#address-cells = <0x2>;
		#size-cells = <0x2>;
		ranges;

		ramoops@0x23f00000 {
			compatible = "ramoops";
			reg = <0x0 0x23f00000 0x0 0x100000>;
			record-size = <0x20000>;
			console-size = <0x20000>;
			ftrace-size = <0x20000>;
		};

		secmon: secmon {
			compatible = "amlogic, aml_secmon_memory";
			reg = <0x0 0x10000000 0x0 0x200000>;
			no-map;
		};

		linux,cma {
			compatible = "shared-dma-pool";
			reusable;
			size = <0x0 0xbc00000>;
			alignment = <0x0 0x400000>;
			linux,cma-default;
		};
	};

Best regards

Heinrich Schuchardt