Unlike the i.MX8MM and i.MX8MN SoCs added earlier, the imx8mp.dtsi configures some clocks at frequencies that are only validated for overdrive mode, i.e., when VDD_SOC is 950 mV. For the Skov i.MX8MP board, we want to run the SoC at the lower voltage of 850 mV though to reduce heat generation and power usage. For this to work, clock rates need to adhere to the limits of the nominal drive mode. This is done by this series: A new imx8mp-nominal.dtsi reconfigures the imx8mp.dtsi clock tree to be compatible with nominal mode, an adaptation to the Linux clock driver makes it sanity check the actual clock rates against the SoC operating mode's constraints and finally the Skov DT makes use of it. Actual configuration of the VDD_SOC rail continues to happen prior to Linux as well as PLL configuration that needs to happen earlier than the kernel running. See the corresponding barebox patch series[1] for details. Note that the barebox series didn't yet include VDD_SOC reconfiguration to 850mV, that would follow once the kernel changes have been merged. [1]: https://lore.kernel.org/barebox/20240503103717.1370636-1-a.fatoum@xxxxxxxxxxxxxx/ --- Ahmad Fatoum (6): dt-bindings: clock: imx8m: document nominal/overdrive properties arm64: dts: imx8mp: Add optional nominal drive mode DTSI arm64: dts: imx8mp: add fsl,nominal-mode property into nominal.dtsi arm64: dts: freescale: imx8mp-skov: fix LDB clock rate configuration arm64: dts: freescale: imx8mp-skov: operate SoC in nominal mode clk: imx8mp: inform CCF of maximum frequency of clocks .../devicetree/bindings/clock/imx8m-clock.yaml | 14 ++ arch/arm64/boot/dts/freescale/imx8mp-nominal.dtsi | 64 +++++++++ .../arm64/boot/dts/freescale/imx8mp-skov-reva.dtsi | 5 +- .../freescale/imx8mp-skov-revb-mi1010ait-1cp1.dts | 19 +-- drivers/clk/imx/clk-imx8mp.c | 147 +++++++++++++++++++++ 5 files changed, 233 insertions(+), 16 deletions(-) --- base-commit: 78d4f34e2115b517bcbfe7ec0d018bbbb6f9b0b8 change-id: 20241217-imx8m-clk-9467763dfcd8 Best regards, -- Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
