From 9fb2856f6842ae7bd6f00a43a404d4002cdbeee3 Mon Sep 17 00:00:00 2001 From: Thomas Hebb Date: Mon, 14 May 2018 17:56:45 -0400 Subject: ARM: dts: chromecast: override bad bootloader memory info On the Chromecast, the bootloader provides us with an ATAG_MEM of start=0x01000000 and size=0x3eff8000. This is clearly incorrect, as the range given encompasses nearly a GiB but the Chromecast only has 512MiB of RAM! Additionally, this causes the kernel to be decompressed at 0x00008000, below the claimed beginning of RAM, and so the boot fails. Since the existing ATAG parsing code runs before the kernel is even decompressed and irrevocably patches the device tree, don't even try to bypass it. Instead, use the "linux,usable-memory" property instead of the "reg" property to define the real range. The ATAG code only overwrites reg, but linux,usable-memory is checked first in the OF driver, so the fact that reg gets changed makes no difference. Signed-off-by: Thomas Hebb Signed-off-by: Jisheng Zhang --- arch/arm/boot/dts/berlin2cd-google-chromecast.dts | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/arch/arm/boot/dts/berlin2cd-google-chromecast.dts b/arch/arm/boot/dts/berlin2cd-google-chromecast.dts index ca24def0ce13..f1767c8a6826 100644 --- a/arch/arm/boot/dts/berlin2cd-google-chromecast.dts +++ b/arch/arm/boot/dts/berlin2cd-google-chromecast.dts @@ -52,7 +52,17 @@ memory@0 { device_type = "memory"; - reg = <0x00000000 0x20000000>; /* 512 MB */ + + /* + * We're using "linux,usable-memory" instead of "reg" here + * because the (signed and encrypted) bootloader that shipped + * with this device provides an incorrect memory range in + * ATAG_MEM. Linux helpfully overrides the "reg" property with + * data from the ATAG, so we can't specify the proper range + * normally. Fortunately, this alternate property is checked + * first by the OF driver, so we can (ab)use it instead. + */ + linux,usable-memory = <0x00000000 0x20000000>; /* 512 MB */ }; leds { -- cgit v1.2.3