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Revert "ARM: uniphier: add weird workaround code for LD20"

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This reverts commit 45f41c134b.

This weird workaround was the best I came up with at that time
to boot U-Boot from TF-A.

I noticed U-Boot successfully boots on LD20 (i.e. CA72 CPU) by using
the latest TF-A.

Specifically, since the following TF-A commit, U-Boot runs at EL2
instead of EL1, and this issue went away as a side-effect.

|commit f998a052fd94ea082833109f25b94ed5bfa24e8b
|Author: Masahiro Yamada <yamada.masahiro@socionext.com>
|Date:   Thu Jul 25 10:57:38 2019 +0900
|
|    uniphier: run BL33 at EL2
|
|    All the SoCs in 64-bit UniPhier SoC family support EL2.
|
|    Just hard-code MODE_EL2 instead of using el_implemented() helper.
|
|    Change-Id: I7ab48002c5205bc8c013e1b46313b57d6c431db0
|    Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

However, if I reverted that, this problem would come back, presumably
because some EL1 code in U-Boot triggers this issue.

Now that commit f8ddd8cbb5 ("arm64: issue ISB after updating system
registers") fixed this issue properly, this weird workaround is no
longer needed irrespective of the exception level at which U-Boot runs.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
This commit is contained in:
Masahiro Yamada 2020-07-09 15:08:11 +09:00
parent 3113c84ba2
commit 1f8e6a670c
2 changed files with 0 additions and 14 deletions
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1
arch/arm/mach-uniphier/arm64/Makefile
View file

@ -1,4 +1,3 @@
# SPDX-License-Identifier: GPL-2.0+
obj-y += mem_map.o
obj-$(CONFIG_ARCH_UNIPHIER_LD20) += lowlevel_init.o

13
arch/arm/mach-uniphier/arm64/lowlevel_init.S
View file

@ -1,13 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Copyright (C) 2017 Socionext Inc.
*/
#include <linux/linkage.h>
ENTRY(lowlevel_init)
/* LD20 needs the following code to boot. I do not know why. */
mrs x0, sctlr_el1
msr sctlr_el1, x0
ret
ENDPROC(lowlevel_init)