[ARM] 3541/2: workaround for PXA27x erratum E7
Patch from Nicolas Pitre
According to the Intel PXA27x Processor Family Specification
Update document (doc.nr. 280071-009) erratum E7, some care must be taken
to locate the disabling and re-enabling of the MMU to the beginning of a
cache line to avoid problems in some circumstances.
Credits to Simon Vogl <simon.vogl@researchstudios.at> for bringing this
up.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 23016f6..9b42b88 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -448,8 +448,11 @@
mov r1, #-1
mcr p15, 0, r3, c2, c0, 0 @ load page table pointer
mcr p15, 0, r1, c3, c0, 0 @ load domain access control
- mcr p15, 0, r0, c1, c0, 0 @ load control register
- mov pc, lr
+ b 1f
+ .align 5 @ cache line aligned
+1: mcr p15, 0, r0, c1, c0, 0 @ load control register
+ mrc p15, 0, r0, c1, c0, 0 @ and read it back to
+ sub pc, lr, r0, lsr #32 @ properly flush pipeline
/*
* All code following this line is relocatable. It is relocated by
diff --git a/arch/arm/mm/proc-xscale.S b/arch/arm/mm/proc-xscale.S
index 535395e..5215386 100644
--- a/arch/arm/mm/proc-xscale.S
+++ b/arch/arm/mm/proc-xscale.S
@@ -138,17 +138,23 @@
* to what would be the reset vector.
*
* loc: location to jump to for soft reset
+ *
+ * Beware PXA270 erratum E7.
*/
.align 5
ENTRY(cpu_xscale_reset)
mov r1, #PSR_F_BIT|PSR_I_BIT|SVC_MODE
msr cpsr_c, r1 @ reset CPSR
+ mcr p15, 0, r1, c10, c4, 1 @ unlock I-TLB
+ mcr p15, 0, r1, c8, c5, 0 @ invalidate I-TLB
mrc p15, 0, r1, c1, c0, 0 @ ctrl register
bic r1, r1, #0x0086 @ ........B....CA.
bic r1, r1, #0x3900 @ ..VIZ..S........
+ sub pc, pc, #4 @ flush pipeline
+ @ *** cache line aligned ***
mcr p15, 0, r1, c1, c0, 0 @ ctrl register
- mcr p15, 0, ip, c7, c7, 0 @ invalidate I,D caches & BTB
bic r1, r1, #0x0001 @ ...............M
+ mcr p15, 0, ip, c7, c7, 0 @ invalidate I,D caches & BTB
mcr p15, 0, r1, c1, c0, 0 @ ctrl register
@ CAUTION: MMU turned off from this point. We count on the pipeline
@ already containing those two last instructions to survive.
