Posts by bkeohane

bkeohane · Jul 7th 2025

Hi,

I indeed used the wrong chokes. The chokes Murata DLP11S need to be used, as stated in your HW documentation.
After removing them, the HDMI works.

Here is a good overview about using chokes in high speed differential layouts: consumer-signal

I will rework my layout.

Thanks. Topic closed.

bkeohane · Jun 24th 2025

I use I2C_C for the SGTL5000 audio codec, and my layout also used I2C_C for the HDMI EDID (SDA,SLC), may this cause the issue of a nun.functional HMDI output? Is there a pinmux for this?

bkeohane · Jun 23rd 2025

Yes, you are correct, I use an eFusa9r2. I accidently posted into armstone, sorry.
I will have a look, thanks for your suggestions!

bkeohane · Jun 12th 2025

Hello,

I have drawn and layoutet a HDMI connector onto a custom board, and I took the SINTF hardware documentation as template.

On SINTF, HDMI is working, but not on my custom board. I took another look at the documentation and realized, there exists a HDMI_DDCCEC_AUX_P pin (J24 plug). This one is not shown on J6 plug. Do we need it?

I have attached the layout and schematic of my custom PCB. Pin 154 is connected to GND while 156 is the HDMI_DDCCEC_AUX_N signal.

Thanks!

bkeohane · Jun 5th 2025

I adjusted my device tree as you porposed, but I am afraid, it did not work.

bkeohane · Jun 5th 2025

In my console output shared before, I noticed:

Code

imx-ipuv3 2400000.ipu: IPU Warning - IPU_INT_STAT_5 = 0x00800000
imx-ipuv3 2400000.ipu: IPU Warning - IPU_INT_STAT_10 = 0x00100000

After some investigation, I come to the conclusion, that clone mode is not stable on this hardware with fbdev.

Would you also relate to this?

bkeohane · Jun 5th 2025

For LVDS, I use

Code

#define CONFIG_EFUSA9_LVDS0_BPP 32
#define CONFIG_EFUSA9_LVDS0_PIX_FMT "RGB888"
#define CONFIG_EFUSA9_LVDS0_DATA_WIDTH 24
#define CONFIG_EFUSA9_LVDS0_MAPPING "spwg"
#define CONFIG_EFUSA9_LVDS0_TIMING \
wvga { \
clock-frequency = <72400000>; \
hactive = <1280>; \
vactive = <800>; \
hfront-porch = <76>; \
hback-porch = <80>; \
hsync-len = <4>; \
vback-porch = <17>; \
vfront-porch = <17>; \
vsync-len = <1>; \
de-active = <1>; \
pixelclk-active = <0>; \
}

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For HDMI, it is

Code

#define CONFIG_EFUSA9_HDMI_BPP 32
#define CONFIG_EFUSA9_HDMI_PIX_FMT "RGB24"
#define CONFIG_EFUSA9_HDMI_MODE_STR "1280x720M@60"

See attached file for full DTS settings. We use a custom display.

bkeohane · Jun 5th 2025

Hello,

Quote

However, I thing it is important to unblank the HDMI display before starting weston with the clone mode.

Is this done correctly?

Yes. Before starting any weston instance, I unblanked fb2. The application on LVDS remains blurry rendered with color shifts.

I have attached the console output, when starting Weston in two instances in clone-mode and starting my GUI app.

Thanks!

bkeohane · Jun 5th 2025

Hi,

thanks for your answer. It works.

However, I experience false colors of the application rendered on the LVDS screen, as soon as I unblank fb2/ clone to the second weston instance on HDMI.

The colors on HDMI are correct, whatsoever. Feel free to check the image I attached, to see what happens.

Any suggestions? I feel, the switch to the open source driver that supports DRM is doable but may be an overload, especially since the HDMI feature shall be very simple.

May any Kernel display driver configs (e.g. IPU settings) or device tree configs help (hardware mirroring)?

Thanks!

bkeohane · Jun 3rd 2025

Hi,

thanks for your answer.

Quote

Another would be to try to use the same framebuffer for both outputs. This however would require the displays to support the same resolution.

Would this be an option?

Our LVDS display is 1280x800, and I set the HDMI resolution to 1280x720 in the device tree. If there are a few pixels missing on the bottom, it is ok. So yes, this would be a quick solution.

Is it also done in the device tree? May it will work, if the HDMI monitor requires hotplugging?

I tried to make the HDMI use the same IPU as LVDS:

Code

#ifdef CONFIG_EFUSA9_HDMI
&hdmi_core {
ipu_id = <0>;
disp_id = <0>;
// ...
}

But it does not work. I assume, it is because of different display timings.

Hence, I am asking myself, how to achive a simple copy of the LVDS output to the HDMI output.

Thank you!

bkeohane · Jun 2nd 2025

Hello, I also have an issue regarding HDMI.

We use efusA9R2 Quad and Yocto. Besides the Primary screen (DISPLAY_LVDS0) our application shall support a second optional screen connected via HDMI. The second screen shall mirror the first one.

- We patched efusa9r2q.dts by setting

Code

+#define CONFIG_EFUSA9_MXCFB0 DISPLAY_LVDS0
+#define CONFIG_EFUSA9_MXCFB1 DISPLAY_HDMI

to enable the display. We were able to display our app via HDMI using EGLFS as follows:

Code

export QT_QPA_PLATFORM=eglfs
export QT_QPA_EGLFS_FB=/dev/fb2
./qt_app

- In our first approach we simply copied the framebuffer using ffmpeg

- local.conf:

- remove wayland and x11: DISTRO_FEATURES:remove = "x11 wayland"

- add ffmpeg: IMAGE_INSTALL:append = " ffmpeg"

- activate HDMI: Done by starting an app like :

Code

export QT_QPA_PLATFORM=eglfs
export QT_QPA_EGLFS_FB=/dev/fb2
./qt_app

- close the app (HDMI is active)

- start ffmpeg

Code

ffmpeg -f fbdev -framerate 30 -i /dev/fb0 -vf "scale=1280:720" -f fbdev /dev/fb2

-> works but it is delay by at least 1 sec

-> the LVDS Display does not Show the Colors correctly

Wayland and Weston

Since a single instance of ur app shall be Display on multiple screens we added wayland/weston to our Image. This works on our Primary Display. However we were not able to get HDMI to work.

Code

IMAGE_INSTALL:append = " weston weston-init qtwayland"

-> weston is started. properly and our app is started.

However the second screen HDMI does not work.

Code

ls /sys/class/drm/

Shows

Code

card0@ renderD128@ Version

-> no HDMI ...

We assume, there is a graphics driver issue on iMX6 and Weston, e.g., the drm driver is not found. Our goal is to let the Qt app discover the second display, and the Qt view instance will make a copy of itself to the second display, when it is found. It works well on Windows. However, on Yocto Linux, it fails, due to the drm driver not being found.

Any hints on how to get a second view of a Qt app running on a HMDI monitor simultaneously would be great, either using EGLFS (which I assume does not work) or Weston.

Thanks in advance!

bkeohane · Dec 19th 2024

Hello,

I've built a core-image-minimal-initramfs image to test its deployment in RAM, and I changed the image type to:

Code

IMAGE_FSTYPES += "cpio.gz.u-boot"

I changed the fdt variable to:

Code

fdt=nand read 12000000 FDT; bootm 11000000 13000000 12000000

I have created a NAND partition "RamDisk", I download and store the initramfs image to RAM address 0x13000000, and I write it to this partition.

I have also changed the variable:

Code

rootfs root=/dev/ram0

When I boot, I run into the following:

Code

Loading from nand0, offset 0x240000
zImage detected
NAND read: device 0 offset 0x1240000, size 0x1c0000 1835008 bytes read: OK
## Booting kernel from zImage at 11000000
## Loading init Ramdisk from Legacy Image at 13000000 ... Image Name: core-image-minimal-initramfs-fsi Image Type: ARM Linux RAMDisk Image (uncompressed) Data Size: 5526515 Bytes = 5.3 MiB Load Address: 00000000 Entry Point: 00000000 Verifying Checksum ... OK
## Flattened Device Tree blob at 12000000 Booting using the fdt blob at 0x12000000 Loading Kernel Image Loading Ramdisk to 4ee0d000, end 4f3523f3 ... OK Using Device Tree in place at 12000000, end 1200ee15 Setting run-time properties
## Overwriting property gpmi-nand@00112000/fus,ecc_strength from device tree!
## Overwriting property bdinfo/ecc_strength from device tree!
## Keeping property bdinfo/board_name from device tree!
Starting kernel ...

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But when the actual rootfs shall be mounted, there is an issue:

Code

Run /init as init process
Starting version 250.5+
mtdblock: MTD device 'NBoot' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'UserDef' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'Refresh' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'UBoot' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'UBootEnv' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'Kernel' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'RamDisk' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'FDT' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'TargetFS' is NAND, please consider using UBI block devices instead.
Waiting for removable media... 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0...
Mounted filesystems
Available block devices
major minor #blocks name
1 0 8192 ram0 1 1 8192 ram1 1 2 8192 ram2 1 3 8192 ram3 1 4 8192 ram4 1 5 8192 ram5 1 6 8192 ram6 1 7 8192 ram7 31 0 256 mtdblock0 31 1 768 mtdblock1 31 2 256 mtdblock2 31 3 768 mtdblock3 31 4 256 mtdblock4 31 5 8192 mtdblock5 31 6 8192 mtdblock6 31 7 1792 mtdblock7 31 8 241664 mtdblock8 179 0 3817472 mmcblk2
Cannot find rootfs.img file in /run/media/* , dropping to a shell

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If I set the rootfs variable back to default:

Code

rootfs=rootfstype=ubifs ubi.mtd=TargetFS root=ubi0:rootfs

The ramdisk image is still successfully read, bit this time, the boot sequence runs into:

Code

Run /init as init process
Starting version 250.5+
mtdblock: MTD device 'UserDef' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'NBoot' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'Refresh' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'UBoot' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'UBootEnv' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'Kernel' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'RamDisk' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'FDT' is NAND, please consider using UBI block devices instead.
mtdblock: MTD device 'TargetFS' is NAND, please consider using UBI block devices instead.
root 'ubi0:rootfs' doesn't exist or does not contain a /dev.

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I assume, there is a problem with handing over from the initramfs to the actual rootfs. Any suggestions?

Thanks!

Bjørn

bkeohane · Dec 16th 2024

I changed

Code

fdt=nand read 12000000 FDT; bootm 11000000 - 12000000

to

Code

fdt=nand read 13000000 FDT; bootm 11000000 - 13000000

which works.

I realized, when creating the rootfs on TargetFS partition, the size is not set correctly. A reboot after setting the partitions solved this issue.

The topic can be regarded as closed,

bkeohane · Dec 16th 2024

I have found the variable

Code

fdt=nand read 12000000 FDT; bootm 11000000 - 12000000

I assume, this needs to be changed, too?

bkeohane · Dec 16th 2024

Hello,

thank you for your answer.

I have setup the partition table accordingly, using the mtdparts env variable:

Code

mtdparts=mtdparts=gpmi-nand:256k(NBoot)ro,768k(UserDef),256k(Refresh)ro,768k(UBoot)ro,256k(UBootEnv)ro,24m(Kernel)ro,1792k(FDT)ro,-(TargetFS)

and I changed fdtaddr to 0x13000000:

Code

efusA9r2 # mtdparts
device nand0 <gpmi-nand>, # parts = 8
#: name size offset mask_flags
0: NBoot 0x00040000 0x00000000 1
1: UserDef 0x000c0000 0x00040000 0
2: Refresh 0x00040000 0x00100000 1
3: UBoot 0x000c0000 0x00140000 1
4: UBootEnv 0x00040000 0x00200000 1
5: Kernel 0x01800000 0x00240000 1
6: FDT 0x001c0000 0x01a40000 1
7: TargetFS 0x0e400000 0x01c00000 0
active partition: nand0,0 - (NBoot) 0x00040000 @ 0x00000000

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However, after installing the new Kernel image, and reinstalling FDT and rootfs image, I run into an error:

Code

NAND read: device 0 offset 0x1a40000, size 0x1c0000
Non-correctable error in page at 0x01a40800
Non-correctable error in page at 0x01a41000
Non-correctable error in page at 0x01a41800
Non-correctable error in page at 0x01a42000
Non-correctable error in page at 0x01a42800
Non-correctable error in page at 0x01a43000
Non-correctable error in page at 0x01a43800
Non-correctable error in page at 0x01a44000
Non-correctable error in page at 0x01a44800
Non-correctable error in page at 0x01a45000
Non-correctable error in page at 0x01a45800
Non-correctable error in page at 0x01a46000
Non-correctable error in page at 0x01a46800
Non-correctable error in page at 0x01a47000
Non-correctable error in page at 0x01a47800
Non-correctable error in page at 0x01a48000
Non-correctable error in page at 0x01a48800
Non-correctable error in page at 0x01a49000
Non-correctable error in page at 0x01a49800
Non-correctable error in page at 0x01a4a000
Non-correctable error in page at 0x01a4a800
Non-correctable error in page at 0x01a4b000
Non-correctable error in page at 0x01a4b800
NAND read failed at 0x01a40000 with error -74
0 bytes read: ERROR
## Booting kernel from zImage at 11000000
## Flattened Device Tree blob at 12000000
Booting using the fdt blob at 0x12000000
Loading Kernel Image
Using Device Tree in place at 12000000, end 1200ee15
fdt_find_or_add_subnode: memory: FDT_ERR_BADSTRUCTURE
ERROR: arch-specific fdt fixup failed
- must RESET the board to recover.
FDT creation failed! hanging...### ERROR ### Please RESET the board ###

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It is weird, that it seems to still look for a FDT at 0x12000000:

Code

## Flattened Device Tree blob at 12000000

May this be the issue? I used the command:

Code

nand write $loadaddr FDT $filesize

to install the FDT. It seems counterintuitive, since the $loadaddr variable holds the address 0x11000000, but the output of writing to NAND was:

Code

efusA9r2 # nand write . FDT $filesize
NAND write: device 0 offset 0x1a40000, size 0xbe16
48662 bytes written: OK

So, it did write to the correct offset, as it seems.

Is there any other address I need to change, or maybe I should use the command:

Code

nand write 0x13000000 FDT $filesize

Thanks again for your support.

bkeohane · Nov 20th 2024

Hello,

I have built an Kernel image with a bundled initramfs, to show a bootscreen very early using Plymouth. The Kernel image is about 20 MB in size. The default partition size for the Kernel (address $Kernel in U-Boot) is 7 MB in size.

I have repartitioned the Kernel partition using mkpart in U-Boot, by taking some memory space from the TargetFS. I made sure, the offsets and sizes of all partitions fit. When downloading and installing the Kernel image incl. initramfs to my Kernel partition, I boot into a kernel panic.

Is there any reason behind this? I asked myself, can I not modify the partitions and its sizes inside a Yocto layer, by e.g., patching the u-boot configuration file (fsimx6.h)?

Any hint on partitioning and making the bundled kernel image run would be helpful!

Thank you.

bkeohane · Nov 20th 2024

Hi,

thank you for the detailed answer. I now see the problem is of bigger concern.

However, I could successfully build an initramfs, bundled with the Kernel in a single image. I use this recipe in my custom layer, and I use Plymouth for bootscreen.

Code

# bootscreen-initramfs-image.bb
SUMMARY = "Custom initramfs image with Plymouth for boot splash"
DESCRIPTION = "An initramfs image including Plymouth to show a boot splash screen."
FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
# Init script is installed
SRC_URI += "file://init"
FILES:${PN} += "/init"
do_install:append() {
install -m 0755 ${WORKDIR}/init ${D}/init
install -d ${D}${datadir}/plymouth/themes/spinner-theme
cp -r ${WORKDIR}/spinner-theme/* ${D}${datadir}/plymouth/themes/spinner-theme/
}
INITRAMFS_SCRIPTS ?= "\
initramfs-framework-base \
initramfs-module-setup-live \
initramfs-module-udev \
"
PACKAGE_INSTALL = " \
${INITRAMFS_SCRIPTS} \
${VIRTUAL-RUNTIME_base-utils} \
udev \
base-passwd \
${ROOTFS_BOOTSTRAP_INSTALL} \
busybox \
e2fsprogs-mke2fs \
udev \
plymouth \
"
# Do not pollute the initrd image with rootfs features
IMAGE_FEATURES = ""
export IMAGE_BASENAME = "bootscreen-initramfs-image"
#export IMAGE_BASENAME = "${MLPREFIX}bootscreen-initramfs-image"
IMAGE_NAME_SUFFIX ?= ""
IMAGE_LINGUAS = ""
LICENSE = "MIT"
#IMAGE_FSTYPES = "${INITRAMFS_FSTYPES}"
IMAGE_FSTYPES = "cpio.gz"
inherit core-image
# Set up Plymouth default configurations
IMAGE_ROOTFS_SIZE = "16384"
IMAGE_ROOTFS_EXTRA_SPACE = "0"
# Add Plymouth configuration and service setup
do_rootfs[depends] += "plymouth:do_populate_sysroot"
IMAGE_INSTALL:append = " plymouth plymouth-theme spinner-theme"
# Plymouth needs systemd and udev for proper functionality in initramfs
SYSTEMD_PACKAGES = "systemd systemd-udevd"
# Use the same restriction as initramfs-module-install
COMPATIBLE_HOST = '(x86_64.*|i.86.*|arm.*|aarch64.*)-(linux.*|freebsd.*)'

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The init file is a simple bash script.

Shell-Script

#!/bin/sh
/sbin/plymouthd --attach-to-session
/sbin/plymouth --show-splash

The spinner theme and all its coresponding files were already located on the Fedora VM.

Of course, one needs to activate the initramfs support in the Kernel configuration.

This page also gives some hints: 12 Building — The Yocto Project ® 5.1.999 documentation

Thanks.

bkeohane · Nov 4th 2024

Hello,

thank you for your answer.

I made the experience, that fbsplash and plymouth both do not start as early in the boot process as the penguins logos used to show up.

I use a systemd service to start the fbsplash.sh script very early:

Code

[Unit]
Description=Run fbsplash splashscreen
DefaultDependencies=no
After=local-fs.target
Before=sysinit.target
[Service]
Type=oneshot
ExecStart=/usr/local/bin/fbsplash.sh
RemainAfterExit=true
[Install]
WantedBy=sysinit.target

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Shell-Script

#!/bin/sh
IMGFILE="/usr/share/splashscreen/splashscreen.ppm"
/usr/local/bin/fbsplash -s "$IMGFILE"

It works, but there are several seconds of black screen until the ppm file appears.

----

The same if true for Plymouth, but here, it completely fails to run at boot.

Plymouth-start.service:

Code

[Unit]
Description=Show Plymouth Boot Screen
DefaultDependencies=no
Wants=systemd-ask-password-plymouth.path systemd-vconsole-setup.service
After=systemd-vconsole-setup.service systemd-udev-trigger.service systemd-udevd.service
Before=systemd-ask-password-plymouth.service basic.target
ConditionKernelCommandLine=!plymouth.enable=0
ConditionVirtualization=!container
IgnoreOnIsolate=true

I also set the UBoot bootargs to:

Code

setenv bootargs 'console=ttymxc3,115200 vt.global_cursor_default=0 quiet splash'

and I changed the plymouth.conf file to:

Code

[Daemon]
Theme=spinner
Device=/dev/fb0

Once the eFus has fully booted, I can manually run the plymouth splashscreen by restarting the plymouth.start.service, but it fails to appear directly after UBoot exited and the Kernel boot sequence is running.

Is there a configuration I am missing?

bkeohane · Oct 31st 2024

What file format shall one use to load an image from RAM to the bootloader using splashprepare/splashimage?

I use a 8bit Bitmap, and it is not shown in original colors. I compressed it to RLE, but UBoot says:

Error: compression type 1 not supported

bkeohane · Oct 31st 2024

Thank you.

My display is working without the patch, but I will test it.

Is there also a way to replace the penguins with a custom image?

Posts by bkeohane

HMDI Schematic

HMDI Schematic

HMDI Schematic

HMDI Schematic

How to enable HDMI video output

How to enable HDMI video output

How to enable HDMI video output

How to enable HDMI video output

How to enable HDMI video output

How to enable HDMI video output

How to enable HDMI video output

Wayland and Weston

Howto initramfs with yocto on efusA7ULL

Repartitioning NAND Flash (via Yocto/ Patch)

Repartitioning NAND Flash (via Yocto/ Patch)

Repartitioning NAND Flash (via Yocto/ Patch)

Repartitioning NAND Flash (via Yocto/ Patch)

U-boot Display

U-boot Display

U-boot Display

U-boot Display