Re: [U-Boot] [PATCH] ppc4xx: Disable trace broadcast for 44x non debug mode

[Stefan Roese]

On Thursday 16 September 2010 20:32:04 Victor Gallardo wrote:
> 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.

Applied to u-boot-ppc4xx/next. Thanks.
 
Cheers,
Stefan

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[U-Boot] [PATCH] ppc4xx: Disable trace broadcast for 44x non debug mode

[Victor Gallardo]

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 
---
 arch/powerpc/cpu/ppc4xx/start.S |3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/cpu/ppc4xx/start.S b/arch/powerpc/cpu/ppc4xx/start.S
index 4bad32f..bac8681 100644
--- a/arch/powerpc/cpu/ppc4xx/start.S
+++ b/arch/powerpc/cpu/ppc4xx/start.S
@@ -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_...@l /* Disable Trace Broadcast */
+   mtspr   SPRN_CCR0,r1
mtspr   SPRN_DBCR0,r0
mtspr   SPRN_DBCR1,r0
mtspr   SPRN_DBCR2,r0
-- 
1.6.1.rc3

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