Il 02/01/24 07:11, Viresh Kumar ha scritto:
On 29-12-23, 18:28, Nícolas F. R. A. Prado wrote:When the mediatek-cpufreq-hw driver enables the hardware (by writing to REG_FREQ_ENABLE), if the regulator supplying the voltage to the big CPUs hasn't probed yet, the platform hangs shortly after and "rcu: INFO: rcu_preempt detected stalls on CPUs/tasks" are printed in the log. To prevent this from happening, describe the big CPUs regulator in the performance-controller DT node, so that devlink ensures the regulator has been probed and configured before the frequency scaling hardware is probed and enabled. Signed-off-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx> --- arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi index dd5b89b73190..505da60eee90 100644 --- a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi +++ b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi @@ -502,6 +502,10 @@ &pcie1 { pinctrl-0 = <&pcie1_pins_default>; };+&performance {+ big-cpus-supply = <&mt6315_6_vbuck1>; +}; + &pio { mediatek,rsel-resistance-in-si-unit; pinctrl-names = "default";I think the regulator needs to be mentioned in the CPU's node and not here ?
Even if the regulator voltage is being changed by firmware with cpufreq-hw, the actual regulators should go to each CPU node and not in the cpufreq driver node, I agree with Viresh. Besides, that's the same thing that we're doing with mediatek-cpufreq as well... and since we're talking about that, we should also do something about this such that we stop declaring `regulator-always-on` for CPU cores in devicetree, but this is probably slightly out of context for what you're trying to do here, so, read that as an "extra consideration" :-) Cheers, Angelo
