QoS & WMM not working on imx6ulz

[oscarmezyk]

Hi,

we are having issue with imx6ulz and WIFI WMM feature - basically the WMM priorities does not work on our board. We are using a module connected on SDIO, from Silabs, but it seems that it is not related to driver/wifi chip itself.

We have tried on RPI3 & RPI0, with several kernels (4.19 & 5.4) with settings as close as possible to each other and WMM does not work on RPI0 and our board. We have tried also another SBC with 4core CortexA53 chip - and it works there as well. We suspect some differences between ARM cores or some specific dts settings that cause QoS services to not work on single core chip. But it's hard to imagine what that would be.

Any hints what to look for? What to check?

[jamesbone]

Hello @oscarmezyk ,

I think you should measure with an Oscilloscope the signals of the SDIO, since, I would think it maybe related to the speed of the SDIO, and this should be related to driver.

But can you share more info, to understand, or reproduced the issue in an EVK board from NXP.

[oscarmezyk]

Hi,

SDIO clock is 4bit/50Mhz - SD High speed - that's max what the module can do and should be enough to run 802.11n at 72mbps. But would the qos/tos queues really depend on the SDIO clock? That seems kind of strange. Additionally - we have tested on RPi3 with 25Mhz and it works there.

I would need to move this topic off the public forum to share more info.