[v3,0/6] arm64: dts: freescale: imx8mp-skov: switch to nominal drive mode

Message

Ahmad Fatoum Jan. 13, 2025, 1:42 p.m. UTC

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/[e-mail]/

---
Changes in v3:
- change boolean mode properties to string property, so it's possible to
  override in overlays (Frank).
- Dropped Conor's Ack again due to aforementioned binding change.
- make struct imx8mp_clock_constraints::clkid unsigned (Stephen)
- Remove comma after sentinel member (Stephen)
- Link to v2: https://lore.kernel.org/r/[e-mail]

Changes in v2:
- Explain in Patch 1/6 why two properties are added instead of one
  (Conor)
- Collect Conor's Acked-by
- Collect Peng's Reviewed-by
- Link to v1: https://lore.kernel.org/r/[e-mail]

---
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     |  11 ++
 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                       | 151 +++++++++++++++++++++
 5 files changed, 234 insertions(+), 16 deletions(-)
---
base-commit: 78d4f34e2115b517bcbfe7ec0d018bbbb6f9b0b8
change-id: 20241217-imx8m-clk-9467763dfcd8

Best regards,