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mx6: Disable Power Down Bit of watchdog

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On a mx6qsabresd revision C board with rev1.2 mx6q, the system gets resetted
and it is not able to reach the Linux prompt.

Comparing the watchdog behaviour on a revB versus revC board:

- On a mx6qsabresd revB:

U-Boot > reset
resetting ...

U-Boot 2013.01-10524-g432a3aa-dirty (Feb 07 2013 - 13:34:46)

CPU:   Freescale i.MX6Q rev1.1 at 792 MHz
Reset cause: WDOG
...

- On a mx6qsabresd revC:

U-Boot > reset
resetting ...

U-Boot 2013.01-10524-g432a3aa-dirty (Feb 07 2013 - 13:34:46)

CPU:   Freescale i.MX6Q rev1.1 at 792 MHz
Reset cause: POR

So due to revC POR/watchdog circuitry whenever a watchdog occurs, it causes a POR.

Clearing the PDE - Power Down Enable bit of WMCR registers fixes the problem and
is also safe for all mx6 boards.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Otavio Salvador <otavio@ossystems.com.br>
Acked-by: Stefano Babic <sbabic@denx.de>
This commit is contained in:
Fabio Estevam 2013-02-07 06:45:23 +00:00 committed by Stefano Babic
parent 7c92c54075
commit 76c91e668a
2 changed files with 20 additions and 0 deletions
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12
arch/arm/cpu/armv7/mx6/soc.c
View file

@ -30,6 +30,7 @@
#include <asm/arch/clock.h>
#include <asm/arch/sys_proto.h>
#include <asm/imx-common/boot_mode.h>
#include <stdbool.h>
struct scu_regs {
u32 ctrl;
@ -121,12 +122,23 @@ void set_vddsoc(u32 mv)
writel(reg, &anatop->reg_core);
}
static void imx_set_wdog_powerdown(bool enable)
{
struct wdog_regs *wdog1 = (struct wdog_regs *)WDOG1_BASE_ADDR;
struct wdog_regs *wdog2 = (struct wdog_regs *)WDOG2_BASE_ADDR;
/* Write to the PDE (Power Down Enable) bit */
writew(enable, &wdog1->wmcr);
writew(enable, &wdog2->wmcr);
}
int arch_cpu_init(void)
{
init_aips();
set_vddsoc(1200); /* Set VDDSOC to 1.2V */
imx_set_wdog_powerdown(false); /* Disable PDE bit of WMCR register */
return 0;
}

8
arch/arm/include/asm/arch-mx6/imx-regs.h
View file

@ -601,5 +601,13 @@ struct iomuxc_base_regs {
u32 daisy[104]; /* 0x7b0..94c */
};
struct wdog_regs {
u16 wcr; /* Control */
u16 wsr; /* Service */
u16 wrsr; /* Reset Status */
u16 wicr; /* Interrupt Control */
u16 wmcr; /* Miscellaneous Control */
};
#endif /* __ASSEMBLER__*/
#endif /* __ASM_ARCH_MX6_IMX_REGS_H__ */