[PATCH v1 2/2] PCI: dw-rockchip: Add runtime PM support to Rockchip PCIe driver

[Anand Moon]

Hi Manivannan

Thanks for your review comment.

On Fri, 31 Oct 2025 at 14:09, Manivannan Sadhasivam <mani at kernel.org> wrote:
>
> On Mon, Oct 27, 2025 at 08:25:30PM +0530, Anand Moon wrote:
> > Add runtime power management support to the Rockchip DesignWare PCIe
> > controller driver by enabling devm_pm_runtime() in the probe function.
> > These changes allow the PCIe controller to suspend and resume dynamically,
> > improving power efficiency on supported platforms.
> >
>
> Seriously? How can this patch improve the power efficiency if it is not doing
> any PM operation on its own?
>
I could verify that runtime power management is active

[root at rockpi-5b alarm]# cat
/sys/devices/platform/a41000000.pcie/power/runtime_status
active
[root at rockpi-5b alarm]#  find /sys -name runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/power/runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/pci_bus/0004:41/power/runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/0004:41:00.0/power/runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/0004:41:00.0/net/enP4p65s0/power/runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/0004:41:00.0/net/enP4p65s0/enP4p65s0-3::lan/power/runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/0004:41:00.0/net/enP4p65s0/enP4p65s0-2::lan/power/runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/0004:41:00.0/net/enP4p65s0/enP4p65s0-1::lan/power/runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/0004:41:00.0/net/enP4p65s0/enP4p65s0-0::lan/power/runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/0004:41:00.0/mdio_bus/r8169-4-4100/power/runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/0004:41:00.0/mdio_bus/r8169-4-4100/r8169-4-4100:00/power/runtime_status
/sys/devices/platform/a41000000.pcie/pci0004:40/0004:40:00.0/0004:41:00.0/mdio_bus/r8169-4-4100/r8169-4-4100:00/hwmon/hwmon11/power/runtime_status

Well, the powertop shows that the runtime power management is enabled
on Radxa Rock 5b,

PowerTOP 2.15     Overview   Idle stats   Frequency stats   Device
stats   Device Freq stats   Tunables   WakeUp
>> Good          Wireless Power Saving for interface wlan0
   Good          VM writeback timeout
   Good          Bluetooth device interface status
   Good          NMI watchdog should be turned off
   Good          Autosuspend for unknown USB device 2-1.3 (8087:0a2b)
   Good          Autosuspend for USB device USB 2.0 Hub [2-1]
   Good          Autosuspend for USB device Generic Platform OHCI
controller [usb1]
   Good          Autosuspend for USB device xHCI Host Controller [usb8]
   Good          Autosuspend for USB device Generic Platform OHCI
controller [usb4]
   Good          Autosuspend for USB device EHCI Host Controller [usb2]
   Good          Autosuspend for USB device xHCI Host Controller [usb6]
   Good          Autosuspend for USB device EHCI Host Controller [usb3]
   Good          Autosuspend for USB device xHCI Host Controller [usb5]
   Good          Autosuspend for USB device xHCI Host Controller [usb7]
   Good          Runtime PM for PCI Device Intel Corporation Wireless
8265 / 8275
   Good          Runtime PM for PCI Device Rockchip Electronics Co., Ltd RK3588
   Good          Runtime PM for PCI Device Rockchip Electronics Co., Ltd RK3588
   Good          Runtime PM for PCI Device Realtek Semiconductor Co.,
Ltd. RTL8125 2.5GbE Controller
   Good          Runtime PM for PCI Device Rockchip Electronics Co., Ltd RK3588
   Good          Runtime PM for PCI Device Samsung Electronics Co Ltd
NVMe SSD Controller SM981/PM981/PM983

PowerTOP 2.15     Overview   Idle stats   Frequency stats   Device
stats   Device Freq stats   Tunables   WakeUp
              Usage     Device name
              1.1%        CPU use
            100.0%        Radio device: rfkill_gpio
            100.0%        runtime-rockchip-gate-link-clk.712
            100.0%        PCI Device: Realtek Semiconductor Co., Ltd.
RTL8125 2.5GbE Controller
            100.0%        runtime-rockchip-gate-link-clk.717
            100.0%        runtime-rockchip-gate-link-clk.714
            100.0%        runtime-rockchip-gate-link-clk.489
            100.0%        runtime-a40000000.pcie
            100.0%        runtime-a40800000.pcie
            100.0%        runtime-rockchip-gate-link-clk.718
            100.0%        runtime-rockchip-gate-link-clk.706
            100.0%        runtime-rockchip-gate-link-clk.708
            100.0%        PCI Device: Intel Corporation Wireless 8265 / 8275
            100.0%        Radio device: btusb
            100.0%        runtime-fcd00000.usb
            100.0%        PCI Device: Samsung Electronics Co Ltd NVMe
SSD Controller SM981/PM981/PM983
            100.0%        Radio device: rfkill_gpio
            100.0%        runtime-fc000000.usb
            100.0%        Radio device: iwlwifi
            100.0%        PCI Device: Rockchip Electronics Co., Ltd RK3588
            100.0%        PCI Device: Rockchip Electronics Co., Ltd RK3588
            100.0%        PCI Device: Rockchip Electronics Co., Ltd RK3588
            100.0%        runtime-rockchip-gate-link-clk.711
            100.0%        runtime-fc400000.usb
            100.0%        runtime-rockchip-gate-link-clk.704
            100.0%        runtime-rockchip-gate-link-clk.701
            100.0%        runtime-rockchip-gate-link-clk.716
            100.0%        runtime-rockchip-gate-link-clk.707
            100.0%        runtime-rockchip-gate-link-clk.709
            100.0%        runtime-rockchip-gate-link-clk.719
            100.0%        runtime-xhci-hcd.1.auto
            100.0%        runtime-feb50000.serial
            100.0%        runtime-rockchip-gate-link-clk.715
            100.0%        runtime-rockchip-gate-link-clk.710

> Again, a pointless patch.
I implemented a .remove patch to ensure proper resource cleanup,
which is a necessary step for successfully enabling and managing
runtime power for the device.
>
> - Mani
Thanks
-Anand