Access to RTC freezes OS

rafaelpita — Thu, 23 Oct 2014 13:47:57 GMT

Hi,

I´m using i.MX6 in a custom board and having problems with the RTC.

The SNVS_LPSRTCLR does not increase, freezing the operating system in the function "rtc_write_sync_lp".

static inline void rtc_write_sync_lp(void __iomem *ioaddr)

{

unsigned int i, count1, count2, count3;

/* Wait for 3 CKIL cycles */

for (i = 0; i < 3; i++) {

/* TKT052983: Do consective reads of LSB of counter

* to ensure integrity

do {

count1 = __raw_readl(ioaddr + SNVS_LPSRTCLR);

count2 = __raw_readl(ioaddr + SNVS_LPSRTCLR);

} while (count1 != count2);

/* Now wait until counter value changes */

do {

count2 = __raw_readl(ioaddr + SNVS_LPSRTCLR);

count3 = __raw_readl(ioaddr + SNVS_LPSRTCLR);

} while (count2 != count3);

} while (count3 == count1);

}

The registers associated with SNVS (0x58 is LPTAR, 0x38 is LPCR, LPLR is 0x34):

0x00: 0x00000000

0x04: 0x80002100

0x08: 0x00000000

0x0C: 0x00000000

0x10: 0x00000000

0x14: 0x80000B00

0x18: 0x00000000

0x1C: 0x00000000

0x20: 0x00000000

0x24: 0x00000000

0x28: 0x00000000

0x2C: 0x00000000

0x30: 0x00000000

0x34: 0x000003FD

0x38: 0x00000020

0x3C: 0x00000000

0x40: 0x00000000

0x44: 0x00000000

0x48: 0x00000000

0x4C: 0x40000000

0x50: 0x00002A16

0x54: 0x112643A5

0x58: 0x542C224D

0x5C: 0x00000000

0x60: 0x00000000

0x64: 0x41736166

0x68: 0x00000000

0x6C: 0x00000000

0x70: 0x00000000

0x74: 0x00000000

0x78: 0x00000000

0x7C: 0x00000000

0x80: 0x00000000

0x84: 0x00000000

The /proc/driver/rtc:

cat /proc/driver/rtc

rtc_time : 15:48:28

rtc_date : 2014-10-01

alrm_time : 15:48:29

alrm_date : 2014-10-01

alarm_IRQ : no

alrm_pending : no

update IRQ enabled : no

periodic IRQ enabled : no

periodic IRQ frequency : 1

max user IRQ frequency : 64

24hr : yes

alarm_IRQ : no

If the battery is removed and replaced the problem is solved ( i had 2 wih this problem, now have only one ).

I do not know what happened to these two boards and not know how to prevent it happening in the next, imagine what would be the tampers, but I understand that they are disabled. Any suggestions?

karinavalencia You can prioritize this thread?

bfac

Re: Access to RTC freezes OS

bfac — Thu, 06 Nov 2014 14:52:59 GMT

Dear, just to give an update on this request, I am working with the customer to understand this issue.

We now understand the SRTC lock issue is caused by the register SNVS_LPLR being locked, we are now working on different fronts to try capturing when this register is set, and if an internal source could be locking it.

BR,

Bruno

topic Access to RTC freezes OS in i.MX Processors

Access to RTC freezes OS

Re: Access to RTC freezes OS