On Thu, Dec 19, 2024 at 08:27:31AM +0100, Ahmad Fatoum wrote: >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. Good to see this. I had same plan to support i.MX9. I see you introduce a new property, how about using a boot pararmeter, saying "mode=nominal" or "mode=overdrive". Then drivers could act accordingly. Regards, Peng > >[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> >
