~~NOCACHE~~
<embed en:templates:tabs_ptxdist_bootstrap>
  <label product_type>Embedded module</label>
  <label lang>en</label>
  <label mod_name>tqma28</label>
  <label mod_name_head>TQMa28</label>
  <label mod_arch>arm</label>
  <label bsp_name>Linux</label>
  <label bsp_name_head>Linux</label>
  <label build_system>ptxdist</label>
  <label build_system_head>PTXdist</label>
</embed>
\\

===== Known Issues =====



===== MBa28 ======
==== RS485 ====
^ RS485 bus block in half-duplex mode  ^^
^ Affects   | RS485 via UARTx   |
^ Issue     | During i.MX28 reset the UARTx.CTS# pin is low by default (CPU internal pull down)  |
^ Effect    | Using the MBa28 RS485 circuitry in a half-duplex slave device or half-duplex multi-master environment may block the RS485 bus during i.MX28 reset.\\ The bus is released as soon as the UARTx.CTS# pin is properly configured by software (e.g. U-Boot, Linux, etc.)  |
^ Solution / Workaround  | Add a 10k pull up to the UARTx.CTS# signal on carrier board  |


----



== TQMa28 & TQMa28-fsl | e-MMC drive strength (SETDSR) ==
  * **Affected hardware revisions**: TQMa28 module REV0200
  * **Impact**: eMMC drive strength (card to host) is too high in card default configuration. This degrades signal integrity and has the potential to degrade the lifetime.
  * **Solution**: use only new linux / u-boot from BSP REV0106 or port the required changes to your bootloader /operating system.
  * **Details**: Starting with hardware REV0200 a new eMMC type with better performance characteristics is used on TQMa28. This eMMC features a configurable drive strength (MMC CMD4 - SET_DSR, see JEDEC Standard No. 84-A441, Table 22)\\ To keep signal integrity and prevent degrading the lifetime of the processor the following configuration step for the eMMC must be implemented:
    * Write 0x0100 + 16 Stuff bits using CMD4 to the card everytime the card is selected using CMD7

  * The current state of the changes needed in BSP REV0106 for:
    * U-Boot 2013.04 (TQMa28/28L): modifies device tree before booting linux to incorporate DSR value for eMMC value
    * U-Boot 2009.08 (TQMa28-fsl): modifies linux command-line to incorporate DSR value for eMMC value
    * Linux 3.10 (TQMa28/28L): value of DSR parsed from device tree property
    * Linux 2.6.35 (TQMa28-fsl): value of DSR parsed from kernel command-line

Both device tree and command-line implement the value as "tq,dsr".

== TQMa28 & TQMa28-fsl | U-Boot | Firmware Updates via SD card ==
  * **Affected Revisions**: 0100, 0101
  * **Issue**: Unable to extract sizes of images on SD card => Unable to calculate required sectors to save image
  * **Workaround**: whole uboot/kernel partitions copied

== TQMa28 | U-Boot | Environment location ==
  * **Affected Revisions**: 0101
  * **Issue**: Environment gets saved to and loaded from hard-coded mmc device 0
  * **Workaround**: none - future release: replace hard-code with dynamic code


== TQMa28 | U-Boot | VDDA Brownout ==
  * **Affected Revisions**: 0101
  * **Issue**: The brownout value of register HW_POWER_VDDA is set to 100 mV below 1.8 V. During boot voltage drops >100mV occur. For the VDDA_BO being too close the device powers down and thus stops after the Kernel line "TCP established hash table entries".
  * **Workaround**: Increase brownout span to 150 mV.\\ --> At the U-Boot prompt type: **mw 80044050 0x0008260c**\\ --> You may also automate this by changing default boot command: **setenv bootcmd "mw 80044050 0x0008260c; $bootcmd"; saveenv**

== TQMa28-fsl | Linux 2.6.35.13 | Ethernet Issue ==
  * **Affected Revisions**: 0101
  * **Issue**: Ethernet link cannot be established to 10 mbit half duplex counterpart
  * **Workaround**: none - fixed in future release

== TQMa28 | Linux 3.5 | GPIO0 IRQ ==
  * **Affected Revisions**: 0101
  * **Issue**: GPIOs on Bank 0 are unusable as interrupt source
  * **Workaround**: Patch included into next BSP revision. See https://community.freescale.com/thread/231371

== TQMa28 | Linux 3.5 | Login as non-root ==
  * **Affected Revisions**: all up to 0103
  * **Issue**: "adduser X; login X" results in message "Killed"
  * **Workaround**: This issue will be fixed in BSP 0103.\\ Until then set Kernel config option CONFIG_DEFAULT_MMAP_MIN_ADDR to 32768. Find it at Kernel features - Low address space to protect from user allocation 

== TQMa28 | Linux 3.5 | USB device connected before boot ==
  * **Affected Revisions**: BSP 0102
  * **Issue**: The Operating System does not recognize USB devices if they are plugged in before boot.
  * **Workaround**: Modify the Devicetree. Add/change at** usb@80090000** the following property **"dr_mode" to "dr_mode = host"**