docs/dasharo-menu-docs: Add APU configuration documentation

Signed-off-by: Michał Żygowski <[email protected]>

Author: miczyg1

docs/dasharo-menu-docs/dasharo-apu-configuration.md

@@ -0,0 +1,43 @@
+# Dasharo APU Configuration
+
+The Dasharo APU Configuration menu is an exclusive menu for PC Engines apu
+platforms. This menu is intended to provide equivalent runtime configuration
+capabilities as [PC Engines sortbootorder](https://github.com/pcengines/sortbootorder).
+
+> Not all sortbootorder options may be currently available. They may be added
+> in the future.
+
+## Dasharo APU Configuration menu options
+
+When entering the `Dasharo APU Configuration` menu, one may see the
+following options to appear:
+
+![](/images/menus/apu_config.jpeg){ class="center" }
+
+### Core Performance Boost
+
+This option enables AMD Core Performance Boost (aka CPU Turbo). When enabled
+firmware will make 2 additional boosted P-states available. Core Performance
+Boost is able to raise a single core frequency from 1000MHz up to 1400MHz if
+other cores are pretty much inactive.
+
+Disable this option if you notice system unstabilities.
+
+### Watchdog
+
+`Enable watchdog` option controls whether the AMD FCH watchdog will be enabled
+during boot. When selected, the `Watchdog timeout value` will appear, where
+one can specify the watchdog expiration timeout in seconds.
+
+The watchdog is useful when a platform hangs and needs to be reset
+automatically, which will happen if watchdog timer expires. Minimum timeout is
+60s to let the OS take control over the watchdog (e.g. sp5100_tco watchdog
+driver for Linux) and keep reloading it to avoid resets.
+
+### PCI Express power management features
+
+When enabled, the firmware will attempt to enable Clock Power Management, ASPM
+L0s and L1 on PCI Express ports. Enabling these options may result in [PCI
+Express device performance
+reduction](https://github.com/pcengines/coreboot/issues/387) at the cost of
+better power savings.

docs/dasharo-menu-docs/overview.md

@@ -48,6 +48,8 @@ In such case please follow the EC firmware update instructions for a specific
 board variant.
 
 * [Setup Main Page](#main-page)
+    - [Dasharo APU Configuration](dasharo-apu-configuration.md) (PC Engines
+      APUs only)
     - [User Password Management](#user-password-management)
     - [Device Manager](device-manager.md)
     - [Dasharo System Features](dasharo-system-features.md)

docs/images/menus/apu_config.jpeg

@@ -347,6 +347,7 @@ nav:
           - 'Boot Maintenance Manager': dasharo-menu-docs/boot-maintenance-mgr.md
           - 'Device Manager': dasharo-menu-docs/device-manager.md
           - 'Dasharo System Features': dasharo-menu-docs/dasharo-system-features.md
+          - 'Dasharo APU Configuration': dasharo-menu-docs/dasharo-apu-configuration.md
       - 'Checkbox certification software usage': common-coreboot-docs/checkbox.md
       - 'Dumping logs': common-coreboot-docs/dumping_logs.md
     # - 'Trolling Topics List':