From 340ffd267c85fc28da7cfd681b177c816af800cf Mon Sep 17 00:00:00 2001 From: Valentine Barshak Date: Sat, 22 Sep 2007 00:50:09 +1000 Subject: [POWERPC] 4xx: 440EPx/GRx incorrect write to DDR SDRAM errata workaround Add a workaround for PowerPC 440EPx/GRx incorrect write to DDR SDRAM errata. Data can be written to wrong address in SDRAM when write pipelining enabled on plb0. We disable it in the cpu_setup for these processors at early init. Signed-off-by: Valentine Barshak Signed-off-by: Josh Boyer --- arch/powerpc/kernel/cpu_setup_44x.S | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) (limited to 'arch/powerpc/kernel/cpu_setup_44x.S') diff --git a/arch/powerpc/kernel/cpu_setup_44x.S b/arch/powerpc/kernel/cpu_setup_44x.S index c790634d946..8e1812e2f3e 100644 --- a/arch/powerpc/kernel/cpu_setup_44x.S +++ b/arch/powerpc/kernel/cpu_setup_44x.S @@ -20,7 +20,14 @@ _GLOBAL(__setup_cpu_440ep) b __init_fpu_44x _GLOBAL(__setup_cpu_440epx) - b __init_fpu_44x + mflr r4 + bl __init_fpu_44x + bl __plb_disable_wrp + mtlr r4 + blr +_GLOBAL(__setup_cpu_440grx) + b __plb_disable_wrp + /* enable APU between CPU and FPU */ _GLOBAL(__init_fpu_44x) @@ -31,3 +38,19 @@ _GLOBAL(__init_fpu_44x) isync blr +/* + * Workaround for the incorrect write to DDR SDRAM errata. + * The write address can be corrupted during writes to + * DDR SDRAM when write pipelining is enabled on PLB0. + * Disable write pipelining here. + */ +#define DCRN_PLB4A0_ACR 0x81 + +_GLOBAL(__plb_disable_wrp) + mfdcr r3,DCRN_PLB4A0_ACR + /* clear WRP bit in PLB4A0_ACR */ + rlwinm r3,r3,0,8,6 + mtdcr DCRN_PLB4A0_ACR,r3 + isync + blr + -- cgit v1.2.3