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bsp/atsam: Improve SDRAM initialization.

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According to the manual, MR has to be read back and a memory barrier has
to be added after MR is written during SDRAM initialization.
This commit is contained in:
Christian Mauderer
2017-08-01 16:48:09 +02:00
committed by Sebastian Huber
parent d00a7d1c22
commit a5d49ebd37
1 changed files with 20 additions and 0 deletions
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20
c/src/lib/libbsp/arm/atsam/libraries/libboard/source/board_memories.c
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@@ -203,6 +203,10 @@ void BOARD_ConfigureSdram(void)
set Mode to 1 in the Mode Register and perform a write access to set Mode to 1 in the Mode Register and perform a write access to
any SDRAM address.*/ any SDRAM address.*/
SDRAMC->SDRAMC_MR = SDRAMC_MR_MODE_NOP; SDRAMC->SDRAMC_MR = SDRAMC_MR_MODE_NOP;
#ifdef __rtems__
(void) SDRAMC->SDRAMC_MR;
__DMB();
#endif /* __rtems__ */
*pSdram = 0; *pSdram = 0;
for (i = 0; i < 100000; i++); for (i = 0; i < 100000; i++);
@@ -211,6 +215,10 @@ void BOARD_ConfigureSdram(void)
The application must set Mode to 2 in the Mode Register and perform a write The application must set Mode to 2 in the Mode Register and perform a write
access to any SDRAM address. */ access to any SDRAM address. */
SDRAMC->SDRAMC_MR = SDRAMC_MR_MODE_ALLBANKS_PRECHARGE; SDRAMC->SDRAMC_MR = SDRAMC_MR_MODE_ALLBANKS_PRECHARGE;
#ifdef __rtems__
(void) SDRAMC->SDRAMC_MR;
__DMB();
#endif /* __rtems__ */
*pSdram = 0; *pSdram = 0;
for (i = 0; i < 100000; i++); for (i = 0; i < 100000; i++);
@@ -220,6 +228,10 @@ void BOARD_ConfigureSdram(void)
SDRAM location eight times.*/ SDRAM location eight times.*/
for (i = 0; i < 8; i++) { for (i = 0; i < 8; i++) {
SDRAMC->SDRAMC_MR = SDRAMC_MR_MODE_AUTO_REFRESH; SDRAMC->SDRAMC_MR = SDRAMC_MR_MODE_AUTO_REFRESH;
#ifdef __rtems__
(void) SDRAMC->SDRAMC_MR;
__DMB();
#endif /* __rtems__ */
*pSdram = 0; *pSdram = 0;
} }
@@ -233,6 +245,10 @@ void BOARD_ConfigureSdram(void)
4 banks) bank address, the SDRAM write access should be done at the address 4 banks) bank address, the SDRAM write access should be done at the address
0x70000000.*/ 0x70000000.*/
SDRAMC->SDRAMC_MR = SDRAMC_MR_MODE_LOAD_MODEREG; SDRAMC->SDRAMC_MR = SDRAMC_MR_MODE_LOAD_MODEREG;
#ifdef __rtems__
(void) SDRAMC->SDRAMC_MR;
__DMB();
#endif /* __rtems__ */
*pSdram = 0; *pSdram = 0;
for (i = 0; i < 100000; i++); for (i = 0; i < 100000; i++);
@@ -251,6 +267,10 @@ void BOARD_ConfigureSdram(void)
/* 10. The application must go into Normal Mode, setting Mode to 0 in the /* 10. The application must go into Normal Mode, setting Mode to 0 in the
Mode Register and performing a write access at any location in the SDRAM. */ Mode Register and performing a write access at any location in the SDRAM. */
SDRAMC->SDRAMC_MR = SDRAMC_MR_MODE_NORMAL; SDRAMC->SDRAMC_MR = SDRAMC_MR_MODE_NORMAL;
#ifdef __rtems__
(void) SDRAMC->SDRAMC_MR;
__DMB();
#endif /* __rtems__ */
*pSdram = 0; *pSdram = 0;
for (i = 0; i < 100000; i++); for (i = 0; i < 100000; i++);