topic i.MX6UL performance issues in i.MX Processors

i.MX6UL performance issues

jsopenrb — Wed, 24 Feb 2016 11:37:24 GMT

For some reason our test i.MX6UL board is running slower than older i.MX28. Changing CCM_ANALOG_PLL_ARMn divider increases the performance slightly, but it's still about 3 times slower in integer calculcations.

What are correct clock register settings for full CPU speed (528MHz). Changing CACRR[ARM_PODF] divider to 0 causes CPU to hang. Is there some specific procedure for changing this bit?

Using U-Boot from Freescale git and vanilla kernel 4.4.2. U-boot is loaded via serial downloader, then Linux kernel is loaded from SD card and booted. Kernel CPU frequency scaling is disabled.

Re: i.MX6UL performance issues

igorpadykov — Thu, 25 Feb 2016 00:35:22 GMT

Hi J

procedure for setting set cpu frequency to 528 MHz one can find in

AN5170 sect.6.4.4. Video Playback: steps , sect.4.3 Dhrystone benchmark.

cache.freescale.com/files/32bit/doc/app_note/AN5170.pdf

For comparing performance of both processors one can run dhrystone using

arm document DAI0273A_dhrystone_benchmarking.pdf.

Best regards

igor

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Re: i.MX6UL performance issues

jsopenrb — Mon, 29 Feb 2016 10:31:03 GMT

It turned out that serial downloader boot happens at some lower frequency which is not switched up correctly in u-boot/kernel. Switching boot mode to boot from fuses solves this issue.