[v2,0/7] PM / devfreq: Add initial imx support
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Message ID cover.1566315740.git.leonard.crestez@nxp.com
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  • PM / devfreq: Add initial imx support
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Leonard Crestez Aug. 20, 2019, 3:45 p.m. UTC
This adds devfreq support for imx8mm, covering dynamic scaling of
internal NOC and DDR Controller

Scaling for simple busses (NIC/NOC) is done through the clk framework
while DRAM scaling is performed in firmware with an "imx-ddrc" wrapper
for devfreq.

Changes since v1:
 * bindings: Stop using "contains" for "compatible"
 * bindings: Set "additionalProperties: false" and document missing stuff.
 * Remove (c) from NXP copyright notice
 * Fix various checkpatch issues
 * Remove unused dram_alt_root clk from imx-ddrc
Link to v1: https://patchwork.kernel.org/project/linux-arm-kernel/list/?series=158773

Changes since RFC v3:
 * Implement passive support and set NOC's parent to DDRC
 * Drop scaling AHB/AXI for now (NOC/DDRC use most power anyway)
 * Stop relying on clk_min_rate
 * Split into two devreq drivers (and bindings) because the ddrc is
really a distinct piece of hardware.
 * Perform DRAM frequency inside devfreq instead of clk, mostly due to
objections to earlier RFCs for imx8m-dram-clk.
 * Fetch info about dram clk parents from firmware instead of
hardcoding in driver. This can more easily support additional rates.
 * Link: https://patchwork.kernel.org/cover/11056779/
 * Link: https://patchwork.kernel.org/patch/11049429/

Scaling buses can cause problems for devices with realtime bandwith
requirements such as display, the intention is to use the interconnect
framework to make DEV_PM_QOS_MIN_FREQUENCY to devfreq. There are
separate patches for that:

* https://patchwork.kernel.org/cover/11104055/
* https://patchwork.kernel.org/cover/11078671/

Leonard Crestez (7):
  clk: imx8m: Set CLK_GET_RATE_NOCACHE on dram_alt/apb
  dt-bindings: devfreq: Add bindings for generic imx buses
  PM / devfreq: Add generic imx bus driver
  dt-bindings: devfreq: Add bindings for imx ddr controller
  PM / devfreq: Add dynamic scaling for imx ddr controller
  PM / devfreq: imx-ddrc: Measure bandwidth with perf
  arm64: dts: imx8mm: Add devfreq nodes

 .../devicetree/bindings/devfreq/imx-ddrc.yaml |  60 ++
 .../devicetree/bindings/devfreq/imx.yaml      |  68 +++
 arch/arm64/boot/dts/freescale/imx8mm.dtsi     |  53 +-
 drivers/clk/imx/clk-imx8mm.c                  |   6 +-
 drivers/clk/imx/clk-imx8mn.c                  |   6 +-
 drivers/clk/imx/clk-imx8mq.c                  |   7 +-
 drivers/devfreq/Kconfig                       |  12 +
 drivers/devfreq/Makefile                      |   1 +
 drivers/devfreq/imx-ddrc.c                    | 514 ++++++++++++++++++
 drivers/devfreq/imx-devfreq.c                 | 148 +++++
 10 files changed, 867 insertions(+), 8 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/devfreq/imx-ddrc.yaml
 create mode 100644 Documentation/devicetree/bindings/devfreq/imx.yaml
 create mode 100644 drivers/devfreq/imx-ddrc.c
 create mode 100644 drivers/devfreq/imx-devfreq.c