On 18.12.2019 17:05, Adam Ford wrote: > On Wed, Dec 18, 2019 at 8:44 AM Leonard Crestez <leonard.crestez@xxxxxxx> wrote: >> >> On 18.12.2019 15:35, Adam Ford wrote: >>> On Fri, Nov 22, 2019 at 3:45 PM Leonard Crestez <leonard.crestez@xxxxxxx> wrote: >>>> >>>> This adds support for dynamic scaling of the DDR Controller (ddrc) >>>> present on i.MX8M series chips. Actual frequency switching is >>>> implemented inside TF-A, this driver wraps the SMC calls and >>>> synchronizes the clk tree. >>>> >>>> DRAM frequency switching requires clock manipulation but during this operation >>>> DRAM itself is briefly inaccessible so this operation is performed a SMC call >>>> to by TF-A which runs from a SRAM area. Upon returning to linux the clock tree >>>> is updated to correspond to hardware configuration. >>>> >>>> This is handled via CLK_GET_RATE_NO_CACHE for dividers but muxes are handled >>>> manually: the driver will prepare/enable the new parents ahead of switching (so >>>> that the expected roots are enabled) and afterwards it will call clk_set_parent >>>> to ensure the parents in clock framework are up-to-date. >>>> >>>> This series is useful standalone and roughly similar to devfreq drivers for >>>> tegra and rockchip. >>>> >>>> Running at lower dram rates saves power but can affect the functionality of >>>> other blocks in the chip (display, vpu etc). Support for in-kernel constraints >>>> will some separately. >>>> >>>> This series has no dependencies outside linux-next. The driver depends >>>> on features from the NXP branch of TF-A and will cleanly fail to probe >>>> on mainline. There are also plans to upstream dram dvfs in TF-A. >>>> >>>> Leonard Crestez (5): >>>> clk: imx8m: Set CLK_GET_RATE_NOCACHE on dram clocks >>>> clk: imx: Mark dram pll on 8mm and 8mn with CLK_GET_RATE_NOCACHE >>>> dt-bindings: memory: Add bindings for imx8m ddr controller >>>> PM / devfreq: Add dynamic scaling for imx8m ddr controller >>>> arm64: dts: imx8m: Add ddr controller nodes >>>> >>>> .../memory-controllers/fsl/imx8m-ddrc.yaml | 72 +++ >>>> arch/arm64/boot/dts/freescale/imx8mm-evk.dts | 18 + >>>> arch/arm64/boot/dts/freescale/imx8mm.dtsi | 10 + >>>> .../boot/dts/freescale/imx8mn-ddr4-evk.dts | 18 + >>>> arch/arm64/boot/dts/freescale/imx8mn.dtsi | 10 + >>>> arch/arm64/boot/dts/freescale/imx8mq-evk.dts | 24 + >>>> arch/arm64/boot/dts/freescale/imx8mq.dtsi | 10 + >>>> drivers/clk/imx/clk-imx8mm.c | 11 +- >>>> drivers/clk/imx/clk-imx8mn.c | 12 +- >>>> drivers/clk/imx/clk-imx8mq.c | 12 +- >>>> drivers/clk/imx/clk-pll14xx.c | 7 + >>>> drivers/clk/imx/clk.h | 1 + >>>> drivers/devfreq/Kconfig | 9 + >>> >>> Since there is a Kconfig change, should there me a defconfig change? >> >> Yes, you need to enable CONFIG_ARM_IMX8M_DDRC_DEVFREQ in order to test >> this. Enabling as "m" should work. > > I enabled it as 'm' but I was more curious to know if we should push > this upstream with the rest of the series. I skipped enabling because it's very experimental; maybe after imx interconnect is also enabled? >>>> drivers/devfreq/Makefile | 1 + >>>> drivers/devfreq/imx8m-ddrc.c | 465 ++++++++++++++++++ >>>> 15 files changed, 670 insertions(+), 10 deletions(-) >>>> create mode 100644 Documentation/devicetree/bindings/memory-controllers/fsl/imx8m-ddrc.yaml >>>> create mode 100644 drivers/devfreq/imx8m-ddrc.c >>> >>> I applied the whole series against 5.5-rc1 and I am trying to test it. >>> I know the 4.14 kernel NXP posted on Code Aurora is capable to >>> lowering the DDRC controller to 25MHz on the 8MM when the video is >>> off. Since there is no video support yet for the 8MM, I was expecting >>> to see the DDRC clock to be at or around 25MHz. >>> >>> Using debug FS, I can see the dram core clock is still running at >>> 750MHz, and measuring power, it shows something consistent with what I >>> see on the Code Aurora kernel with video turned on and the clock at >>> 750MHz. >>> >>> Is there some way to get the dram_core_clk to drop to 25MHz to see >>> some power reduction? The same commands used in the Yocto build don't >>> apply here since we don't have video. >> >> Current upstream driver just keeps current frequency by default. Try the >> following: >> >> cd /sys/class/devfreq/devices/devfreq0 > > can't cd to /sys/class/devfreq/devices/devfreq0: No such file or directory > > I did some checking and I found: > imx8m-ddrc-devfreq 3d400000.memory-controller: failed to init > firmware freq info: -19 > > Was there some prerequisite patches I needed to apply before your series? You need a recent version of TF-A from nxp ( upstream). Try this: https://source.codeaurora.org/external/imx/imx-atf/log/?h=imx_4.19.35_1.1.0 Or this: https://github.com/cdleonard/arm-trusted-firmware/commits/imx_2.0.y_busfreq Support on upstream ATF is not yet available -- Regards, Leonard
