i.MX6QP + Qt5 Cinematic graphics issue

[gary_bisson]

Hi,

Running the Qt5 Cinematic Experience shows some graphics issues on 6QP only.

Here are some details on the setup to reproduce the issue:

- Qt5.5 or Qt5.6 (tested with both)

- Yocto Jethro or Buildroot master (as of today, for latest graphics libraries support)

- Using a platform that supports both 6Q and 6QP, in my case the Nitrogen6_MAX and Nitrogen6QP_MAX, the cpu is the only difference

- Kernel 3.14.53, in my case:

GitHub - boundarydevices/linux-imx6 at boundary-imx_3.14.52_1.1.0_ga: Boundary Devices Kernel tree f...

   -> this issue was also present with 3.14.38-6qp-beta + p6.x libraries, but at the time it was beta so not worth mentioning

- imx-gpu-viv + kernel-module-imx-gpu-viv version 5.0.11 p7.4

- Qt5 Cinematic Experience:

http://quitcoding.com/download/Qt5_CinematicExperience_rpi_1.0.tgz

meta-qt5/cinematicexperience_1.0.bb at master · meta-qt5/meta-qt5 · GitHub

Please find attached two screenshots, one shows the output when running on a 6Q, the other is running on the 6QP, using the exact same SDCard, exact same kernel, only the device tree differs (includes imx6q.dtsi in one case, imx6qp.dtsi in the other).

Please dismiss the tearing that can be seen in those screenshots, this is due to the software used to grab the framebuffer (fbgrab) which doesn't wait for vsync. Instead, focus on the rectangles around the different stars that appears on the background. It sounds like some alpha blending isn't managed properly on the 6QP.

Let me know if you have any question regarding the issue, which hopefully will be fixed in next Vivante release.

Regards,

Gary

[gusarambula]

Hello Gary Bisson,

Our team will investigate so I would need to ask you for some patience.

In the meantime, would it be possible for you to reproduce this issue on an NXP board using the latest NXP BSP release?

Regards,

[VladanJovanovic]

Reproduced on i.MX 6QP SABRE SDB. Please see here:

iMX6 Quad Plus Display issue

[gary_bisson]

Hi Vladan,

Thanks, but your link goes to a unauthorized page. Can you grant me access?

Regards,

Gary

[gusarambula]

Hello Gary Bisson,

I'm not sure if you got access granted. But in summary the issue was reproduced. Export FB_MULTI_BUFFER=3 shall fix the issue.

Two buffers seem not to be enough. Next release will most likely have three by default.

Regards,

[gary_bisson]

Hi gusarambula​,

No I still don't have access to the issue, please grant me the access.

I confirm what Danielle said, this FB_MULTI_BUFFER export does NOT change anything, the issue is still present. Please make sure to look at my screenshots and Danielle's to understand/reproduce the issue.

Regards,

Gary

[gusarambula]

Hello Gary Bisson,

I've added the information from Danielle's Post to the escalation and we'll keep you informed. (I'm not sure if you may be granted access to the internal escalation though)

Regards,

[gary_bisson]

Hi,

Thanks for the update.

Unfortunately I only have Boundary Devices platforms which is why I pointed to both the source code and the Yocto recipe of the Qt5 Cinematic demo so anyone could build the app for testing.

Let me know if you need anything else.

Regards,

Gary

[gusarambula]

Hello Gary Bisson,

I understand. Please have a bit of patience and we'll update this thread when we have more information on this matter.

Regards,

[gary_bisson]

Hi,

I confirm the bug exists with both X11 and FB/EGLFS back-ends.

Here is another app that shows the same issue:

qt5-nmap-carousel-demo - NotABug.org: Free code hosting

Regards,

Gary

[danielleloader]

We are also experiencing this issue on a custom iMX6Q based board.

We have made up some boards with QuadPlus parts which show this issue in our Qt SceneGraph based apps as well the Cinematic demo - exactly as in your screenshots. The same apps running on the original non-Plus boards do not exhibit the issue.

So far we have not been able to find any way to improve the situation through framebuffer settings, Qt and/or EGLFS configuration.