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65920 ignores VAUX2 configuration after warm reset

Ken Brown13794
Prodigy 200 points

Our board needs VAUX2 to be 2.5V.  I modified our u-boot to write the appropriate value to the VAUX2_DEDICATED register to achieve that.

After cold boot, this works fine, and the scope confirms that VAUX2 is in fact 2.5V.

After a warm reset, the same boot path occurs.  But when u-boot writes to VAUX2_DEDICATED as before, VAUX2 does not change from 1.8V to 2.5V.  It stays 1.8V.  And if I read back the VAUX2_DEDICATED register, it isn't changed - the value that I readback is not what I wrote.

I've verified that MSECURE is high, though from my reading of the manual, the setting of MSECURE should not matter, I think.

So why would the 65920 apparently become read-only all of a sudden (at least for the VAUX2_DEDICATED register).???

  • 0
    Intellectual 370 points

    Hi Ken,

     

    On Warm reset, the VAUX2 VSEL value goes to warmreset state, in warmreset state, VSEL is set back to default state.

    Before, changing the VSEL, you will have to put the resource into ACTIVE state again.

    If you will try to change VSEL in WARMRESET state, it will not have any impact.

     

    Let me know, if this is clear.

     

    Regards
    Ankit

  • 0 in reply to Ankit Somani15962
    Prodigy 200 points

    Thanks Ankit, that was the problem.

    I had loaded a warm reset power sequence into the 65920, and that left VAUX2 in WARMRESET state.  Once I changed it to leave VAUX2 in ACTIVE state, I can set the VSEL field as expected.