Poor fps performance of tdx-reference-multimedia-image on iMX7D eMMC

Technical Support
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1

I tried to evaluate the performance of Colibri iMX7D (eMMC) and so I downloaded and built the Linux Reference Muiltimedia image from here.

Everything works fine and I’m able to run the image and to install and run my “Hello World” application.

The image comes with the well known Qt Cinematic Experience Demo, and runnign it I can see that the fps performance are poor. Basically the application is freezed (0 fps on the to-left corner of the screen).

The same happens to my custom Qt application (QtQuick based).

I investigated a little bit and I found this on Toradex community.

The explanation is really good and it clarifies what happens to QtQuick/QML application on non-GPU hardware (as iMX7 is). It refers to old Qt 5.7 and 5.8, but it’s almost the same on Qt 5.15.

The suggestion is to add the environment variable QMLSCENE_DEVICE=softwarecontext.

I did it inside my custom Hello World and it did the trick.

I wonder why this environment variable is not automatically added in the Linux Reference Image for iMX7D.

It seems that without this, Qt demos on the image can’t be used on iMX7 hardware.

Can you clarify, please?

2

Could you please specify version of tdx-reference-multimedia-image you were testing?

3

Hello @alex.tx
I followed this KB for BSP 5.0.0 and so I cloned the repo
repo init -u https://git.toradex.com/toradex-manifest.git -b dunfell-5.x.y -m tdxref/default.xml

This should point to the following default.xml

<?xml version="1.0" encoding="UTF-8"?>
<manifest>
  <remote alias="repo" fetch="https://github.com/meta-qt5" name="githq"/>

  <include name="base/pinned.xml"/>
  <include name="bsp/pinned-nxp.xml"/>
  <include name="bsp/pinned-tdx.xml"/>

  <project name="meta-qt5.git" path="layers/meta-qt5" remote="githq" revision="0d8eb956015acdea7e77cd6672d08dce18061510" upstream="dunfell"/>
  <project name="meta-toradex-demos.git" path="layers/meta-toradex-demos" remote="tdx" revision="82e3d7b2b56fccabcd52708314acc9dfd6bb24d1" upstream="dunfell-5.x.y"/>
  <project name="meta-toradex-distro.git" path="layers/meta-toradex-distro" remote="tdx" revision="632db61f177acf18df79d40fefdf1c662c6233a8" upstream="dunfell-5.x.y">
    <copyfile dest="export" src="buildconf/export"/>
  </project>
</manifest>
4

Hello @vix ,

We had internal discussions in the past about this, and now in the latest images, we have removed qt-cinematic on non-GPU modules (ull and imx7). There it should just show an analog clock. And yes, this env variable is not added in our images.

Best Regards, Janani

5

Hello @saijanani.tx

the image on imx7 shows an analog clock at the boot.

Bu the cinematic experience demo is available on the filesystem. And if a user launches it, it’s unusable.

I think that if you have reasons to remove the example for non-GPU modules (and you could have), you should remove it from the filesystem too.

6

Hello @vix ,

Thank you for your feedback. We will consider it.

BR, Janani