On 2021-03-19 11:05, Daniel Lezcano wrote:
The DTPM framework is looking for upstream SoC candidates to share the
power numbers.
We can see around different numbers but the one which seems to be
consistent with the initial post for the values on the CPUs can be
found in the patch https://lore.kernel.org/patchwork/patch/810159/
The kernel hacker in me would be more inclined to trust the BSP that the
vendor actively supports than a 5-year-old patch that was never pursued
upstream. Apparently that was last updated more recently:
https://github.com/rockchip-linux/kernel/commit/98d4505e1bd62ff028bd79fbd8284d64b6f468f8
The ex-mathematician in me can't even comment either way without
evidence that whatever model expects to consume this value is even
comparable to whatever "arm,mali-simple-power-model" is. The way the
latter apparently needs an explicit "static" coefficient as well as a
"dynamic" one, and the value here being nearly 3 times that of a
similarly-named one in active use downstream (ChromeOS appears to still
be using the values from before the above commit), certainly incline me
to think they may not be...
I don't know the precision of this value but it is better than
nothing.
But is it? If it leads to some throttling mechanism kicking in and
crippling GPU performance because it's massively overestimating power
consumption, that would be objectively worse for most users, no?
Robin.
Hopefully, one day SoC vendors will be more generous with the power
numbers at least for the SoC which are from the previous generation
and give the community the opportunity to develop power based
frameworks.
---
arch/arm64/boot/dts/rockchip/rk3399.dtsi | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
index edbbf35fe19e..1ab1d293d2e9 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
@@ -1933,6 +1933,7 @@
interrupt-names = "job", "mmu", "gpu";
clocks = <&cru ACLK_GPU>;
#cooling-cells = <2>;
+ dynamic-power-coefficient = <977>;
power-domains = <&power RK3399_PD_GPU>;
status = "disabled";
};
