diff options
Diffstat (limited to 'target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch')
| -rw-r--r-- | target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch b/target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch new file mode 100644 index 0000000000..034d5b52fc --- /dev/null +++ b/target/linux/bcm53xx/patches-4.19/300-ARM-BCM5301X-Disable-MMU-and-Dcache-during-decompres.patch @@ -0,0 +1,101 @@ +From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl> +Date: Wed, 24 Sep 2014 22:14:07 +0200 +Subject: [PATCH] ARM: BCM5301X: Disable MMU and Dcache during decompression +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +Broadcom devices have broken CFE (bootloader) that leaves hardware in an +invalid state. It causes problems with booting Linux. On Northstar +devices kernel was randomly hanging in ~25% of tries during early init. +Hangs used to happen at random places in the start_kernel. On BCM53573 +kernel doesn't even seem to start booting. + +To workaround this problem we need to do following very early: +1) Clear 2 following bits in the SCTLR register: +#define CR_M (1 << 0) /* MMU enable */ +#define CR_C (1 << 2) /* Dcache enable */ +2) Flush the whole D-cache +3) Disable L2 cache + +Unfortunately this patch is not upstreamable as it does above things +unconditionally. We can't check if we are running on Broadcom platform +in any safe way and doing such hacks with ARCH_MULTI_V7 is unacceptable +as it could break other devices support. + +Signed-off-by: Rafał Miłecki <rafal@milecki.pl> +--- + +--- a/arch/arm/boot/compressed/Makefile ++++ b/arch/arm/boot/compressed/Makefile +@@ -35,6 +35,11 @@ ifeq ($(CONFIG_ARCH_ACORN),y) + OBJS += ll_char_wr.o font.o + endif + ++ifeq ($(CONFIG_ARCH_BCM_5301X),y) ++OBJS += head-bcm_5301x-mpcore.o ++OBJS += cache-v7-min.o ++endif ++ + ifeq ($(CONFIG_ARCH_SA1100),y) + OBJS += head-sa1100.o + endif +--- /dev/null ++++ b/arch/arm/boot/compressed/head-bcm_5301x-mpcore.S +@@ -0,0 +1,37 @@ ++/* ++ * ++ * Platform specific tweaks. This is merged into head.S by the linker. ++ * ++ */ ++ ++#include <linux/linkage.h> ++#include <asm/assembler.h> ++#include <asm/cp15.h> ++ ++ .section ".start", "ax" ++ ++/* ++ * This code section is spliced into the head code by the linker ++ */ ++ ++__plat_uncompress_start: ++ ++ @ Preserve r8/r7 i.e. kernel entry values ++ mov r12, r8 ++ ++ @ Clear MMU enable and Dcache enable bits ++ mrc p15, 0, r0, c1, c0, 0 @ Read SCTLR ++ bic r0, #CR_C|CR_M ++ mcr p15, 0, r0, c1, c0, 0 @ Write SCTLR ++ nop ++ ++ @ Call the cache invalidation routine ++ bl v7_flush_dcache_all ++ nop ++ mov r0,#0 ++ ldr r3, =0x19022000 @ L2 cache controller, control reg ++ str r0, [r3, #0x100] @ Disable L2 cache ++ nop ++ ++ @ Restore ++ mov r8, r12 +--- a/arch/arm/boot/compressed/cache-v7-min.S ++++ b/arch/arm/boot/compressed/cache-v7-min.S +@@ -12,6 +12,7 @@ + + #include <linux/linkage.h> + #include <linux/init.h> ++#include <asm/assembler.h> + + __INIT + +@@ -63,7 +64,7 @@ loop2: + ARM( orr r11, r11, r9, lsl r2 ) @ factor index number into r11 + THUMB( lsl r6, r9, r2 ) + THUMB( orr r11, r11, r6 ) @ factor index number into r11 +- mcr p15, 0, r11, c7, c14, 2 @ clean & invalidate by set/way ++ mcr p15, 0, r11, c7, c6, 2 @ clean & invalidate by set/way + subs r9, r9, #1 @ decrement the index + bge loop2 + subs r4, r4, #1 @ decrement the way |