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AM3352: Warm reset stops functioning after Linux upgrade to 4.19.152

Benjamin Maximov
Prodigy 20 points
Part Number: AM3352

Hello!

We upgraded the linux kernel from 4.4.xx. Everything works fine except the WARM RESET on pin NRESETIN_OUT.

Before booting the kernel the device restarts when driving NRESETIN low (which means hardware is OK). After the kernel is loaded the pin has no effect. My question is which driver or config option of the kernel is responsible for handling external warm reset?

Regards!

  • 0
    TI__Mastermind 30536 points

    Hi,

    I need to consult with some colleagues to get some concrete ideas for you. I should be able to reply in the next two days.

    Thank you.

  • 0 in reply to RonB
    TI__Mastermind 30536 points

    Hello,

    After discussing this, we have the following queries:

    Who is asserting the reset? Is there an external microcontroller? Or just a push button?
    To be sure, after the kernel is booted, nRESETIN_OUT has no effect and kernel continues as nothing happened? No logs?
    Finally, can you please compare the setting for PRM_RSTTIME register between both versions?
    Thank you.
  • 0 in reply to RonB
    Prodigy 20 points

    Hi RonB,

    We managed to identify the problem. It was a reset button, connected through 20ohm resistor to ground. That resistor was unable to pull down the reset line below the treshold for a reset. After removing it and tying the button directly to the ground, the reset is functioning normally. Maybe the reason is the new kernel version drivers setting the nRESETIN_OUT as output, and the old version - as input.

    Thank you!