MIPS: DB1200: Set Config[OD] for improved stability.

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>
To: Linux-MIPS <linux-mips@linux-mips.org>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Patchwork: https://patchwork.linux-mips.org/patch/2347/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 9 insertions, 2 deletions

diff --git a/arch/mips/alchemy/common/setup.c b/arch/mips/alchemy/common/setup.c
index 561e5da2658b..1b887c868417 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 4a8980027ecf..1dac4f27d334 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);