[PATCH 1/9] MIPS: DB1200: Set Config[OD] for improved stability.

[Manuel Lauss <manuel.lauss@googlemail.com>]

Setting Config[OD] gets rid of a _LOT_ of spurious CPLD interrupts,
but also decreases overall performance a bit.

Signed-off-by: Manuel Lauss <manuel.lauss@googlemail.com>
---
Resend of a patch I submitted earlier.
V2: fix up issues pointed out by Sergei Shtylyov.

 arch/mips/alchemy/common/setup.c           |    4 ++--
 arch/mips/alchemy/devboards/db1200/setup.c |    7 +++++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/mips/alchemy/common/setup.c b/arch/mips/alchemy/common/setup.c
index 561e5da..1b887c8 100644
--- a/arch/mips/alchemy/common/setup.c
+++ b/arch/mips/alchemy/common/setup.c
@@ -52,8 +52,6 @@ void __init plat_mem_setup(void)
 	/* this is faster than wasting cycles trying to approximate it */
 	preset_lpj = (est_freq >> 1) / HZ;
 
-	board_setup();  /* board specific setup */
-
 	if (au1xxx_cpu_needs_config_od())
 		/* Various early Au1xx0 errata corrected by this */
 		set_c0_config(1 << 19); /* Set Config[OD] */
@@ -61,6 +59,8 @@ void __init plat_mem_setup(void)
 		/* Clear to obtain best system bus performance */
 		clear_c0_config(1 << 19); /* Clear Config[OD] */
 
+	board_setup();  /* board specific setup */
+
 	/* IO/MEM resources. */
 	set_io_port_base(0);
 	ioport_resource.start = IOPORT_RESOURCE_START;
diff --git a/arch/mips/alchemy/devboards/db1200/setup.c b/arch/mips/alchemy/devboards/db1200/setup.c
index 4a89800..1dac4f2 100644
--- a/arch/mips/alchemy/devboards/db1200/setup.c
+++ b/arch/mips/alchemy/devboards/db1200/setup.c
@@ -23,6 +23,13 @@ void __init board_setup(void)
 	unsigned long freq0, clksrc, div, pfc;
 	unsigned short whoami;
 
+	/* Set Config[OD] (disable overlapping bus transaction):
+	 * This gets rid of a _lot_ of spurious interrupts (especially
+	 * wrt. IDE); but incurs ~10% performance hit in some
+	 * cpu-bound applications.
+	 */
+	set_c0_config(1 << 19);
+
 	bcsr_init(DB1200_BCSR_PHYS_ADDR,
 		  DB1200_BCSR_PHYS_ADDR + DB1200_BCSR_HEXLED_OFS);
 
-- 
1.7.5.rc3