gcnano-binaries 6.4.7 has flickering issues

[AGamb.5]

Hello,

Here's the context of my issue.

• I'm using buildroot 2022.11 to build a rootfs for a custom stm32mp157 board using a LCD display;
• the Linux kernel is 5.10.116 (https://github.com/STMicroelectronics/linux/tree/v5.10-stm32mp);
• the GUI app is built using the Qt5.15 QML framework.

After the buildroot team upgraded the gcnano binaries package to v6.4.7 I'm facing flickering issues with the display. To figure out if the gcnano binaries are the root cause, I manually downgraded the gcnano to v6.4.3 in which the flickering issue is not present.

I can confirm that the same rootfs/kernel with the gcnano binaries 6.4.3 has no flickering issue.

Find attached to this post two videos :

• one showing that everything works fine with gcnano 6.4.3;
• one showing the flickering issue with gcnano 6.4.7.

The display is mandatory for our product and we can not accept flickering issues like this one.

How can we fix this issue ?

Let me know if you need more traces or tests.

Best Regards

Alexandre Gambier

[Olivier GALLIEN · Accepted solution]

Hi @AGamb.5​ ,

This question has been answered in context of an OLS ticket you raised in parallel.( BZ 145849 )

For community awareness this is ST answer :

There's depedances between gcnano and OpenSTLinux versions.

gcnano 6.4.7 is integrated in DV4.x release ( kernel 5.15) and cannot be used in DV3.x ( kernel 5.10)

ST recommend sticking on the version provided with the OSTL release.

Olivier

[AGamb.5]

Thanks for your reply.

However, since we can't switch to yocto or upgrate the kernel without having to re-validate everything, the answer is a recommendation from ST and not a solution.

[Olivier GALLIEN]

Hi @AGamb.5​ ,

For buildroot users like you I see that bootlin release the support of DV4 / kernel 5.15.

Updated Buildroot support for STM32MP1 platforms - Bootlin's blog

So no constraint to switch to Yocto.

Is that can enable a smoother transition for you?

Olivier

[AGamb.5]

Hi Olivier,

The latest LTS buildroot 2023.02 supports gcnano 6.4.9.

Is there a change log or a document that describe which kernel is recommended with which gcnano binaries ?

If we upgrade the kernel to v5.15 can you confirm me that there's no flickering issue with gcnano 6.4.9 ?

Thanks

Alex

[Olivier GALLIEN]

Hi @AGamb.5​ ,

gcnano 6.4.9 has been integrated and validated in so call DV4.1

STM32 MPU ecosystem release note - stm32mpu

With following component version :

• Linux kernel v5.15-stm32mp-r2 (v5.15.67)
• TF-A v2.6-stm32mp-r2
• U-Boot v2021.10-stm32mp-r2
• OP-TEE 3.16.0-stm32mp-r2
• OpenOCD version v0.11.0

I don't know if LTS buildroot 2023.02 embed those versions.

Worth to ask our partner bootlin about it.

BR,

Olivier

[AGamb.5]

Thanks those information.

We'll check this out.

Our defconfig include the kernel v5.10.*** from the STM github.

For now we don't want to upgrade the kernel otherwise we'll have to re-validate everything.

Our product is battery powered (recharged by solar panel) and we made a big effort in the suspend state of the state so the battery is not drained too fast. That's the main reason why we don't want to change a part as important as the kernel.

We'll investigate it and figure out what we can do.

Thanks again.

[Olivier GALLIEN]

Hi @AGamb.5​ ,

I understood your constraint.

Unfortunately, I cannot guarantee a glitch free integration of gcnano 6.4.9 with our V5.10** Kernel.

Why do you want to upgrade the GPU driver?

Thanks

Olivier

[AGamb.5]

Hi Olivier,

It's true that I haven't thought to check if the GPU driver could be easily updated. My bad.

Do you think if I just update the file located in drivers/gpu/drm/stm/ using those from 5.15 it could compile ?

I'll give a try.

thanks

[Olivier GALLIEN]

Hi @AGamb.5​ ,

No again, ST cannot guarantee this will work.

BR,

Olivier