arm64: dts: rockchip: Add OPP data for CPU cores on RK3588
By default the CPUs on RK3588 start up in a conservative performance mode. Add frequency and voltage mappings to the device tree to enable dynamic scaling via cpufreq. OPP values are adapted from Radxa's downstream kernel for Rock 5B [1], stripping them down to the minimum frequency and voltage combinations as expected by the generic upstream cpufreq-dt driver, and also dropping those OPPs that don't differ in voltage but only in frequency (keeping the top frequency OPP in each case). Note that this patch ignores voltage scaling for the CPU memory interface which the downstream kernel does through a custom cpufreq driver, and which is why the downstream version has two sets of voltage values for each OPP (the second one being meant for the memory interface supply regulator). This is done instead via regulator coupling between CPU and memory interface supplies on affected boards. This has been tested on Rock 5B with u-boot 2023.11 compiled from Collabora's integration tree [2] with binary bl31 and appears to be stable both under active cooling and passive cooling (with throttling) [1] https://github.com/radxa/kernel/blob/stable-5.10-rock5/arch/arm64/boot/dts/rockchip/rk3588s.dtsi [2] https://gitlab.collabora.com/hardware-enablement/rockchip-3588/u-bootSigned-off-by: Alexey Charkov <alchark@gmail.com> Link: https://lore.kernel.org/r/20240617-rk-dts-additions-v5-6-c1f5f3267f1e@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>
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