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ppc4xx: Disable trace broadcast for 44x non debug mode 

By default the trace broadcast is enabled on 44x systems.

To reduce power consumption when instruction tracing is
not needed, disable trace broadcast.

Check External Debug Mode (EDM) bit to detect if it should be
disabled or not.

Resetting system via a debugger will set the DBCR0[EDM] bit.
Resetting via u-boot or OS will not.

Signed-off-by: Victor Gallardo <vgallardo@apm.com>
Signed-off-by: Stefan Roese <sr@denx.de>
This commit is contained in:
Victor Gallardo 2010-09-16 11:32:04 -07:00 committed by Stefan Roese
parent e02d449644
commit ad876fff34
1 changed files with 3 additions and 0 deletions
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3
arch/powerpc/cpu/ppc4xx/start.S
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@ -340,6 +340,9 @@ _start_440:
mfspr r1,SPRN_DBCR0
andis. r1, r1, 0x8000 /* test DBCR0[EDM] bit */
bne skip_debug_init /* if set, don't clear debug register */
mfspr r1,SPRN_CCR0
ori r1,r1,CCR0_DTB@l /* Disable Trace Broadcast */
mtspr SPRN_CCR0,r1
mtspr SPRN_DBCR0,r0
mtspr SPRN_DBCR1,r0
mtspr SPRN_DBCR2,r0