A53 Reset iMX8

Hideo_Noda · ‎04-03-2021

Hi, I'm trying to reset A53 Cores in iMX8PLUS. The bits<3-0> in the register SRC_A53RXR0 at 0x30390004 reset the cores. It works well while u-boot is running on the Core0 but it does not work while Yocto-Linux is running. The registers value was 0x000a0000 which means no-write protection. Does anyone know the reason of the no-work of the reset bits during Yocto-Linux?

igorpadykov · ‎04-04-2021

Hi Hideo

for reset most reliable way is to use CPU WDOG_B Reset signal described on p.11

SPF-46368 schematic

i.MX 8M Plus LPDDR4 EVK Compute Module Design Files

Best regards
igor

Hideo_Noda · ‎04-04-2021

Thank you, igor.

I understand.
Assertion of WDOG_B by clearing the bit <5> WDA of the 16-bit register WDOG1_WCR at 0x30280000 reseted and successfully restarted the whole system.
Is this register accessible by M7 core as well? M7 seems freezed after accessing the register WDOG1_WCR.

Best regards
Hideo

igorpadykov · ‎04-05-2021

Hi Hideo

one can try to set WDOG1 RDC permission for M7 core in

https://source.codeaurora.org/external/imx/imx-atf/tree/plat/imx/imx8m/imx8mp/imx8mp_bl31_setup.c?h=...

Best regards
igor

Hideo_Noda · ‎04-05-2021

Thank you, igor.

I'll look into the code.