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

[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 <vgallardo@apm.com>
---
 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_DTB at l /* Disable Trace Broadcast */
+	mtspr	SPRN_CCR0,r1
 	mtspr	SPRN_DBCR0,r0
 	mtspr	SPRN_DBCR1,r0
 	mtspr	SPRN_DBCR2,r0
-- 
1.6.1.rc3

[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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