Release Notes unified i.MX 91/93 Linux BSP
==========================================

BSP-Yocto-NXP-i.MX93-PD26.1.0          2026-03-13
BSP-Yocto-NXP-i.MX91-PD26.1.0          2026-03-13
=================================================
- Linux NXP Vendor Kernel v6.12.34-2.1.0-phy9 (based on NXP tag lf-6.12.34-2.1.0)
- U-boot v2025.04-2.1.0-phy9 (based on NXP tag lf-6.12.34-2.1.0)
- Yocto 5.2.2 (walnascar)
- Qt 6.8.3
- RAUC 1.14

Tested Yocto Images:
--------------------
- phytec-headless-image
* imx93-phyflex-libra-rdk-1
* phyboard-nash-imx93-1
* phyboard-segin-imx93-2
* phyboard-segin-imx91-1

- phytec-qt6demo-image
* imx93-phyflex-libra-rdk-1
* phyboard-nash-imx93-1
* phyboard-segin-imx93-2
* phyboard-segin-imx91-1

Build Environment:
------------------
- Ubuntu 24.04 64-Bit

Features:
---------
- Added support for phyFLEX-i.MX93 Libra RDK board.
- Switched to ampliphy-boot which means FIT booting is now enabled by default.
  See BSP documentation for implications and more details about ampliphy-boot.
- On phyBOARD-Nash-i.MX93, PWM fan is now controlled entirely by the kernel drivers.
  The userspace application fancontrol is thus not pre-installed in the BSP anymore.
- Ethernet interface names and order are now set by systemd's Predictable Network
  Interface Names. Classic kernel interface naming "ethX" has thus been replaced by
  the systemd's "endX" scheme.
- The ADC is now handled by the IIO rescale and hwmon subsystem which automatically
  handle conversion to physical units (mA, mV).
- SoM options are now entirely handled by the U-Boot board code (no more overlays).
- Added support for phyCAM-VM020 camera on phyBOARD-Nash-i.MX93.
- phyBOARD-Segin-i.MX91/93 AC158 display is EOL. New replacement display is AC220 in
  combination with the PEB-AV-18 A/V adapter.
- System reset on phyCORE-i.MX91/93 SoMs is now performed via the system PMIC rather
  than the watchdog reset line.

Issues fixed:
-------------
- Occasional data loss observed when using DMA with i.MX 93 UART ports is not
  present anymore.

Known Issues:
-------------
- On phyBOARD-Nash-i.MX 93 carrier-board (rev 1616.0), Audio with PEB-AV-10 A/V
  adapter is broken due to HW bug.
- On phyBOARD-Nash-i.MX 93 carrier-board (rev 1616.0 and rev 1616.1), Backlight
  with PEB-AV-10 A/V adapter is ON by default after power-reset due to HW bug.
- Suspend/resume is broken on phyFLEX-i.MX93 Libra RDK board. As a workaround,
  it is possible to disable PM async operations with the command:
    echo 0 > /sys/power/pm_async
  to get a working suspend/resume.
- On the phyFLEX-i.MX93 Libra RDK board (Rev. 1618.2), RS485 and USB-C (X18) mode
  switching during operation (Device to Host) do not work due to a hardware bug.
  To use USB-C in Host mode (e.g., with a USB stick), the USB device must be
  connected before the system boots.

Notes:
------
- With phyBOARD-Nash-i.MX 93 rev 1616.2 the polarity of the SOM Ethernet
  PHY-LEDs has changed from active-low to active-high. This is since the
  PHY-LED pins have also bootstrap functionality:
    (LED0 == RX_DV_En, and LED1 == ANeg_Dis)
  The changed polarity assures that those bootstraps get to the required
  voltage level.
  Since release PD24.2.1 the BSP implements this change of the LED polarity in
  the ethernet drivers of u-boot and Linux kernel.

  Customers using custom carrier board designs are advised to make the same
  change, by adding MOSFETs between ENET2 LED signals and LEDs of RJ45
  connector as in the schematics of the phyBOARD-Nash-i.MX 93 rev 1616.2.

  For those carrier boards that dont have the PHY LEDs polarity change
  (to active-high) one can use the kernels device-tree property
  "ti,leds-polarity". It restores the old kernel behavior of the PHY LEDs
  (active-low). See device-tree for phyBOARD-Segin-i.MX 93
  (imx93-phyboard-segin.dts) as example.
- Due to NXP errata ERR052675:
    "I/O: High frequency operation impacted due voltage
     stress when operating at 3.3V."
  the display pixel clock and camera pixel clock are limited to 52MHz @ 3.3V
  since BSP release PD24.2.1.
  When one of the clocks is configured with more than 52MHz in the device-tree,
  the display driver or camera driver will stop with ERANGE error.
- Occasional system freeze had been observed under certain temperature and load
  conditions. The issue is mitigated by disabling CPU idle management (by
  adding cpuidle.off=1 to kernel command line). NXP has also recommended
  disabling CPU idle management, as especially in extended temperature range
  (e.g. at -40 C) switching off CPUs can have unexpected effects. Please note,
  that by disabling CPU idle management, power consumption of the SOM increases
  (10-50 mW average, 300 mW peak).