sunxi: Watchdog reboot fails on Allwinner R40 after Linux boot

[Fabio Estevam]

On Sun, May 24, 2026 at 9:41 AM Fabio Estevam <festevam at gmail.com> wrote:
>
> Hi,
>
> I am seeing a reboot failure on an Allwinner R40-based board
> (Boardcon EMA40i) running mainline Linux v6.18 or also 7.1.0-rc4-next-20260522.
> This board hasn't been upstreamed yet, but I plan to do so soon.
>
> The board reboots correctly from U-Boot 2026.04 using the sunxi watchdog,
> but Linux fails to reboot even when programming the watchdog
> registers with the exact same values used by U-Boot.

This is solved now. The problem was that the X32KIN R40 pin was not
getting a 32kHz
from the external PCF8563 CLKOUT pin.