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Handle imx6 erratum ERR004346... to reboot, clear the SRS bit twice within

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the same cycle of the 32khz clock.

I've never actually noticed this error happening, but it's an easy fix.
This commit is contained in:
Ian Lepore 2017-01-24 02:09:30 +00:00
parent d592868ebf
commit 83988d944b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=312679
1 changed files with 7 additions and 0 deletions
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7
sys/arm/freescale/imx/imx_machdep.c
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@ -69,11 +69,18 @@ imx_wdog_cpu_reset(vm_offset_t wdcr_physaddr)
* Trigger an immediate reset by clearing the SRS bit in the watchdog
* control register. The reset happens on the next cycle of the wdog
* 32KHz clock, so hang out in a spin loop until the reset takes effect.
*
* Imx6 erratum ERR004346 says the SRS bit has to be cleared twice
* within the same cycle of the 32khz clock to reliably trigger the
* reset. Writing it 3 times in a row ensures at least 2 of the writes
* happen in the same 32k clock cycle.
*/
if ((pcr = devmap_ptov(wdcr_physaddr, sizeof(*pcr))) == NULL) {
printf("cpu_reset() can't find its control register... locking up now.");
} else {
*pcr &= ~WDOG_CR_SRS;
*pcr &= ~WDOG_CR_SRS;
*pcr &= ~WDOG_CR_SRS;
}
for (;;)
continue;