[PATCH 01/13] mach-snapdragon: Fix EL2 boot on DragonBoard 410c

[Stephan Gerhold]

The workaround for the "PSCI bug" on DragonBoard 410c implemented in
arch/arm/mach-snapdragon/include/mach/boot0.h clobbers the x0 register
by storing the CurrentEL in there. When running in EL1, the mode switch
sequence implemented there later clears the register again, but this is
skipped when U-Boot is booted in EL2.

This causes crashes in the mach-snapdragon board_fdt_blob_setup() later,
because the invalid address stored in x0 gets dereferenced to check if it
points to a valid DTB.

We can't rely on having a valid values in the CPU registers for the first
stage bootloader configuration on DB410c, and nothing would place a DTB
there anyway. Skip selecting the SAVE_PREV_BL_FDT_ADDR option for the boot0
hook case to avoid crashing with the clobbered register value.

Fixes: 059d526af312 ("mach-snapdragon: generalise board support")
Signed-off-by: Stephan Gerhold <stephan.gerhold at linaro.org>
---
 arch/arm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 63aefeda9575fec8fc57194358df0819397d088e..af3d39196ee4fb201d4aad20a882bbbb39263396 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1115,7 +1115,7 @@ config ARCH_SNAPDRAGON
 	select SPMI
 	select BOARD_LATE_INIT
 	select OF_BOARD
-	select SAVE_PREV_BL_FDT_ADDR
+	select SAVE_PREV_BL_FDT_ADDR if !ENABLE_ARM_SOC_BOOT0_HOOK
 	select LINUX_KERNEL_IMAGE_HEADER if !ENABLE_ARM_SOC_BOOT0_HOOK
 	select SYSRESET
 	select SYSRESET_PSCI

-- 
2.47.2