For some reason the AT91rm9200 lowlevel init writes to a bunch of
reserved or read-only addresses. All the boards seem to define the
value-to-be-written values as zero ... but they shouldn't actually
be writing *anything* there.
No documented erratum justifies these accesses. It looks like maybe
some pre-release BDI-2000 setup code has been carried along by cargo
cult programming since at least late 2004 (per GIT history).
Here's a patch disabling what seems to be bogosity. Tested on a
csb337; there were no behavioral changes.
---
cpu/arm920t/at91rm9200/lowlevel_init.S | 14 ++------------
include/configs/at91rm9200dk.h | 5 -----
include/configs/at91rm9200ek.h | 5 -----
include/configs/cmc_pu2.h | 5 -----
include/configs/csb637.h | 5 -----
include/configs/m501sk.h | 5 -----
include/configs/mp2usb.h | 5 -----
7 files changed, 2 insertions(+), 42 deletions(-)
--- a/cpu/arm920t/at91rm9200/lowlevel_init.S
+++ b/cpu/arm920t/at91rm9200/lowlevel_init.S
@@ -81,6 +81,7 @@ LoopOsc:
bne 0b
/* delay - this is all done by guess */
ldr r0, =0x00010000
+ /* (vs reading PMC_SR for LOCKA, LOCKB ... or MOSCS earlier) */
1:
subs r0, r0, #1
bhi 1b
@@ -108,16 +109,6 @@ LoopOsc:
.ltorg
SMRDATA:
- .word AT91C_MC_PUIA
- .word CONFIG_SYS_MC_PUIA_VAL
- .word AT91C_MC_PUP
- .word CONFIG_SYS_MC_PUP_VAL
- .word AT91C_MC_PUER
- .word CONFIG_SYS_MC_PUER_VAL
- .word AT91C_MC_ASR
- .word CONFIG_SYS_MC_ASR_VAL
- .word AT91C_MC_AASR
- .word CONFIG_SYS_MC_AASR_VAL
.word AT91C_EBI_CFGR
.word CONFIG_SYS_EBI_CFGR_VAL
.word AT91C_SMC_CSR0
@@ -128,8 +119,7 @@ SMRDATA:
.word CONFIG_SYS_PLLBR_VAL
.word AT91C_MCKR
.word CONFIG_SYS_MCKR_VAL
- /* SMRDATA is 80 bytes long */
- /* here there's a delay of 100 */
+ /* here there's a delay */
SMRDATA1:
.word AT91C_PIOC_ASR
.word CONFIG_SYS_PIOC_ASR_VAL
--- a/include/configs/at91rm9200dk.h
+++ b/include/configs/at91rm9200dk.h
@@ -45,11 +45,6 @@
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
#define CONFIG_SYS_USE_MAIN_OSCILLATOR 1
/* flash */
-#define CONFIG_SYS_MC_PUIA_VAL 0x00000000
-#define CONFIG_SYS_MC_PUP_VAL 0x00000000
-#define CONFIG_SYS_MC_PUER_VAL 0x00000000
-#define CONFIG_SYS_MC_ASR_VAL 0x00000000
-#define CONFIG_SYS_MC_AASR_VAL 0x00000000
#define CONFIG_SYS_EBI_CFGR_VAL 0x00000000
#define CONFIG_SYS_SMC_CSR0_VAL 0x00003284 /* 16bit, 2 TDF, 4 WS */
--- a/include/configs/at91rm9200ek.h
+++ b/include/configs/at91rm9200ek.h
@@ -56,11 +56,6 @@
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
#define CONFIG_SYS_USE_MAIN_OSCILLATOR 1
/* flash */
-#define CONFIG_SYS_MC_PUIA_VAL 0x00000000
-#define CONFIG_SYS_MC_PUP_VAL 0x00000000
-#define CONFIG_SYS_MC_PUER_VAL 0x00000000
-#define CONFIG_SYS_MC_ASR_VAL 0x00000000
-#define CONFIG_SYS_MC_AASR_VAL 0x00000000
#define CONFIG_SYS_EBI_CFGR_VAL 0x00000000
#define CONFIG_SYS_SMC_CSR0_VAL 0x00003284 /* 16bit, 2 TDF, 4 WS */
--- a/include/configs/cmc_pu2.h
+++ b/include/configs/cmc_pu2.h
@@ -44,11 +44,6 @@
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
#define CONFIG_SYS_USE_MAIN_OSCILLATOR 1
/* flash */
-#define CONFIG_SYS_MC_PUIA_VAL 0x00000000
-#define CONFIG_SYS_MC_PUP_VAL 0x00000000
-#define CONFIG_SYS_MC_PUER_VAL 0x00000000
-#define CONFIG_SYS_MC_ASR_VAL 0x00000000
-#define CONFIG_SYS_MC_AASR_VAL 0x00000000
#define CONFIG_SYS_EBI_CFGR_VAL 0x00000000
#define CONFIG_SYS_SMC_CSR0_VAL 0x100032ad /* 16bit, 2 TDF, 4 WS */
--- a/include/configs/csb637.h
+++ b/include/configs/csb637.h
@@ -45,11 +45,6 @@
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
#define CONFIG_SYS_USE_MAIN_OSCILLATOR 1
/* flash */
-#define CONFIG_SYS_MC_PUIA_VAL 0x00000000
-#define CONFIG_SYS_MC_PUP_VAL 0x00000000
-#define CONFIG_SYS_MC_PUER_VAL 0x00000000
-#define CONFIG_SYS_MC_ASR_VAL 0x00000000
-#define CONFIG_SYS_MC_AASR_VAL 0x00000000
#define CONFIG_SYS_EBI_CFGR_VAL 0x00000000
#define CONFIG_SYS_SMC_CSR0_VAL 0x00003284 /* 16bit, 2 TDF, 4 WS */
--- a/include/configs/m501sk.h
+++ b/include/configs/m501sk.h
@@ -46,11 +46,6 @@
*/
#define CONFIG_SYS_USE_MAIN_OSCILLATOR 1
/* flash */
-#define CONFIG_SYS_MC_PUIA_VAL 0x00000000
-#define CONFIG_SYS_MC_PUP_VAL 0x00000000
-#define CONFIG_SYS_MC_PUER_VAL 0x00000000
-#define CONFIG_SYS_MC_ASR_VAL 0x00000000
-#define CONFIG_SYS_MC_AASR_VAL 0x00000000
#define CONFIG_SYS_EBI_CFGR_VAL 0x00000000
#define CONFIG_SYS_SMC_CSR0_VAL 0x00003284 /* 16bit, 2 TDF, 4 WS */
--- a/include/configs/mp2usb.h
+++ b/include/configs/mp2usb.h
@@ -49,11 +49,6 @@
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
#define CONFIG_SYS_USE_MAIN_OSCILLATOR 1
/* flash */
-#define CONFIG_SYS_MC_PUIA_VAL 0x00000000
-#define CONFIG_SYS_MC_PUP_VAL 0x00000000
-#define CONFIG_SYS_MC_PUER_VAL 0x00000000
-#define CONFIG_SYS_MC_ASR_VAL 0x00000000
-#define CONFIG_SYS_MC_AASR_VAL 0x00000000
#define CONFIG_SYS_EBI_CFGR_VAL 0x00000000
#define CONFIG_SYS_SMC_CSR0_VAL 0x00003084 /* 16bit, 2 TDF, 4 WS */
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