Re: [PATCH V2] DT: rockchip: Fix stability issues with the 'performance' governor on rock960

From: Heiko Stuebner
Date: Tue Oct 30 2018 - 10:18:20 EST

Am Mittwoch, 17. Oktober 2018, 11:18:30 CET schrieb Daniel Lezcano:
> When the performance governor is set as default, the rock960 hangs
> around one minute after booting, whatever the activity is (idle, key
> pressed, loaded, ...).
> Based on the commit log found at
> "vdd_log has no consumer and therefore will not be set to a specific
> voltage. Still the PWM output pin gets configured and thence the vdd_log
> output voltage will changed from it's default. Depending on the idle
> state of the PWM this will slightly over or undervoltage the logic supply
> of the RK3399 and cause instability with GbE (undervoltage) and PCIe
> (overvoltage). Since the default value set by a voltage divider is the
> correct supply voltage and we don't need to change it during runtime we
> remove the rail from the devicetree completely so the PWM pin will not
> be configured."
> After removing the vdd-log from the rock960's specific DT, the board
> does no longer hang and shows a stable behavior.
> Apply the same change for the rock960 by removing the vdd-log from the
> DT.
> Fixes: 874846f1fccd ("arm64: dts: rockchip: add 96boards RK3399 Ficus board")
> Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>

applied as fix for 4.20
after including a stable-tag (board entered in previous kernel version)
and modified subject line a bit.