Add two short sections to the common K3 phyCORE docs. Describe the default boot flow and its deprecated version. And write down the use of the watchdog.
Signed-off-by: Wadim Egorov <[email protected]> --- doc/board/phytec/k3-common.rst | 47 ++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/doc/board/phytec/k3-common.rst b/doc/board/phytec/k3-common.rst index ffb50b51ad6..3adb176ea8a 100644 --- a/doc/board/phytec/k3-common.rst +++ b/doc/board/phytec/k3-common.rst @@ -1,6 +1,53 @@ .. SPDX-License-Identifier: GPL-2.0+ .. sectionauthor:: Wadim Egorov <[email protected]> +Boot Flow +--------- + +The default `bootcmd` performs three steps: + +.. code-block:: + + run start_watchdog; bootflow scan -lb; run ${boot}boot + +Boot devices are scanned in the order given by `boot_targets`: + +.. code-block:: + + mmc1 mmc0 spi_flash dhcp + +For each device, U-Boot tries the boot methods listed in `bootmeths`: + +.. code-block:: + + [rauc] script efi extlinux pxe + +The `rauc` bootmeth is only present when `CONFIG_BOOTMETH_RAUC=y` is set in +the A53 defconfig. RAUC slot selection is handled entirely by the bootmeth; +no environment-side configuration is required. + +The legacy `${boot}boot` chain (`mmcboot`, `spiboot`, `netboot`) is kept for +backwards compatibility and prints a deprecation warning when run. New +deployments should rely on the standard boot mechanism (`bootflow`) only. + + +Watchdog +-------- + +`bootcmd` runs `start_watchdog` before starting the boot flow. When +`CONFIG_WATCHDOG_TIMEOUT_MSECS` is set to a non-zero value and the +`watchdog` environment variable points to a watchdog device, U-Boot enables +the watchdog with that timeout. + +After this point the OS is responsible for servicing the watchdog. If it +does not feed the watchdog before the timeout expires, the SoC will reset. +Make sure the watchdog driver is enabled and configured in the kernel and +userspace before relying on this. + +To skip the watchdog start, either build with `CONFIG_WATCHDOG_TIMEOUT_MSECS=0` +or set `watchdog_timeout_ms=0` in the environment. + + Environment ----------- -- 2.48.1
