i.MX ProcessorsのトピックBug in busfreq driver

Bug in busfreq driver

maximkuk — Wed, 25 Apr 2018 13:47:12 GMT

Hello!

On our custom board (imx6d + lpddr2, pop-package) we faced with kernel panic after some tome of work. After some reserces I detected that busfreq causes this.

The thing is that before change ddr frequancy, driver (in function "update_lpddr2_freq_smp") compares new freq value with current and if they equals it returns 0. After that driver configures clock parents and if frequancies not configured before it (because update_lpddr2_freq_smp doesn't actually work) system crashes.

Some times in "update_lpddr2_freq_smp" curr_ddr_rate doesn't changes after previous call. Make it volatile not help. If not check curr_ddr_rate - all works perfect.

Why curr_ddr_rate doesn't change sometimes? And do we need curr_ddr_rate if all other work doings unconditionally?

Re: Bug in busfreq driver

igorpadykov — Wed, 25 Apr 2018 23:31:57 GMT

Hi Maxim

please try ddr test and use nxp bsps described on below link

i.MX6/7 DDR Stress Test Tool V2.80

i.MX Software|NXP

https://source.codeaurora.org/external/imx/linux-imx/tree/?h=imx_4.1.15_2.0.0_ga linux-imx - i.MX Linux kernel

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

Re: Bug in busfreq driver

maximkuk — Thu, 26 Apr 2018 07:04:05 GMT

Thank you for answer and useful links!

It looks like I found the same solution - update curr_ddr_rate before changing ddr frequency.