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[ARM] 3541/2: workaround for PXA27x erratum E7

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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>
This commit is contained in:
Nicolas Pitre 2006-07-01 21:29:32 +01:00 committed by Russell King
parent 3f8efdbe73
commit 2dc7667b9d
2 changed files with 12 additions and 3 deletions
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7
arch/arm/boot/compressed/head.S
View file

@ -448,8 +448,11 @@ __common_mmu_cache_on:
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

8
arch/arm/mm/proc-xscale.S
View file

@ -138,17 +138,23 @@ ENTRY(cpu_xscale_proc_fin)
* 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.