IMX35 performance slowing down after kernel update to 5.4.84

[samwise01]

Hi All,

We were using i.MX35 with kernel 2.6.35.3 in our product and recently we updated the kernel to 5.4.84 expecting better performance and quality. Instead we have seen more issues and performance is very low. For example 

RAM read write speed

In 2.6 was 76.1 MB/s and 42.5 MB/s respectively

In 5.4.259 it is 30.1 MB/s and 17.5 MB/s respectively

SPI ethernet with KS8851

In 2.6 turn around time was just 3 - 4ms and in 5.4 it is 12 ms also iperf shows bandwidth is almost half.

We run yocto danny and just updated the kernel to 5.4. Anyone facing similar issue? Is it even recommended or anyone can point me to kernel - imx processor compatibility sheet?

Thanks 

Sameer

[Bio_TICFSL]

Hello,

It looks like you need update the device tree since kernel 2.6 was in the driver.

Regards

[samwise01]

Hi, we did update the device tree and all the peripherals are up and running. Only change we observe is everything is getting slower. Also as I checked ks8851 was not changed so no idea what would cause the processor to slow down this way