Am Freitag, dem 17.09.2021 um 09:28 +0200 schrieb Heiko Thiery:

Hi Frieder,

Am Mi., 15. Sept. 2021 um 14:09 Uhr schrieb Frieder Schrempf
[off-list ref]:

quoted

On 15.09.21 14:05, Michael Walle wrote:

quoted

Am 2021-09-15 14:03, schrieb Heiko Thiery:

quoted

The buck2 output of the PMIC is the VDD core voltage of the cpu.
Switching off this will poweroff the CPU. Add the 'regulator-always-on'
property to avoid this.

Mh, have this ever worked? Is there a commit which introduced a regression?

Yes, this did work before, even without 'regulator-always-on'. I
currently don't understand why this is needed. The regulator is
referenced in the CPU nodes as 'cpu-supply'. This should be enough to
not disable it as long as the CPU is up.

I rechecked that with 5.11, 5.10 and 5.9 and I see on all of them the
same issue:

[ 31.716031] vdd-5v: disabling
[ 31.719032] rst-usb-eth2: disabling
[ 31.722553] buck2: disabling

While on that I tried to compare with other boards and see that they
also have the cpu-voltage marked as "regulator-always-on". The only
exception in dts/freescale is in imx8mq-librem5-devkit.dts [1] that
has not set this property.

I agree with you and don't understand why this is happening. Has
anyone else an explanation?

[1] https://elixir.bootlin.com/linux/latest/source/arch/arm64/boot/dts/freescale/imx8mq-librem5-devkit.dts#L319

Maybe your kernel config is missing the cpufreq driver, so you don't
have a consumer of the regulator?

Marking the regulator as always-on seems like the right thing to do,
you don't want to depend on a consumer showing up to make sure that
your CPU voltage isn't cut...

Regards,
Lucas


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