Hi Dragan,
On 2024-10-10 12:19, Dragan Simic wrote:
Until the TSADC, thermal zones, thermal trips and cooling maps are defined in the RK3308 SoC dtsi, none of the CPU OPPs except the slowest one may be enabled under any circumstances. Allowing the DVFS to scale the CPU cores up without even just the critical CPU thermal trip in place can rather easily result in thermal runaways and damaged SoCs, which is bad.
Thus, leave only the lowest available CPU OPP enabled for now.
This feel like a very aggressive limitation, to only allow the opp-suspend rate, that is not even used under normal load.
I let my Rock Pi S board with a RK3308B variant run "stress -c 8" for around 10 hours and the reported temp only reach around 50-55 deg c, ambient temp around 20 deg c and board laying flat on a table without any enclosure or heat sink.
This was running with performance as scaling_governor and cpu running the 1008000 opp.
Most RK3308 variants datasheets list 1.3 GHz as max rate for CPU, the K-variant lists 1.2 GHz, and the -S-variants seem to have both reduced voltage and max rate.
The OPPs for this SoC already limits max rate to 1 GHz and is more than likely good enough to not reach the max temperature of 115-125 deg c as rated in datasheets and vendor DTs.
Adding the tsadc and trips (same/similar as px30) will probably allow us to add/use the "missing" 1.2 and 1.3 GHz OPPs.
Regards, Jonas
Fixes: 6913c45239fd ("arm64: dts: rockchip: Add core dts for RK3308 SOC") Cc: stable@vger.kernel.org Signed-off-by: Dragan Simic dsimic@manjaro.org
arch/arm64/boot/dts/rockchip/rk3308.dtsi | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/arm64/boot/dts/rockchip/rk3308.dtsi b/arch/arm64/boot/dts/rockchip/rk3308.dtsi index 31c25de2d689..a7698e1f6b9e 100644 --- a/arch/arm64/boot/dts/rockchip/rk3308.dtsi +++ b/arch/arm64/boot/dts/rockchip/rk3308.dtsi @@ -120,16 +120,19 @@ opp-600000000 { opp-hz = /bits/ 64 <600000000>; opp-microvolt = <950000 950000 1340000>; clock-latency-ns = <40000>;
status = "disabled";status = "disabled";status = "disabled";
Linux-rockchip mailing list Linux-rockchip@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-rockchip