From 113f44ed50d274447a3b76cf250989a423f179a5 Mon Sep 17 00:00:00 2001 From: Manivannan Sadhasivam Date: Thu, 15 Jan 2026 12:59:01 +0530 Subject: PCI/pwrctrl: Add 'struct pci_pwrctrl::power_{on/off}' callbacks To allow the pwrctrl core to control the power on/off sequences of the pwrctrl drivers, add the 'struct pci_pwrctrl::power_{on/off}' callbacks and populate them in the respective pwrctrl drivers. The pwrctrl drivers still power on the resources on their own now. So there is no functional change. Co-developed-by: Krishna Chaitanya Chundru Signed-off-by: Krishna Chaitanya Chundru Signed-off-by: Manivannan Sadhasivam Signed-off-by: Bjorn Helgaas Tested-by: Chen-Yu Tsai Reviewed-by: Bartosz Golaszewski Link: https://patch.msgid.link/20260115-pci-pwrctrl-rework-v5-9-9d26da3ce903@oss.qualcomm.com --- include/linux/pci-pwrctrl.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/pci-pwrctrl.h') diff --git a/include/linux/pci-pwrctrl.h b/include/linux/pci-pwrctrl.h index 4aefc7901cd1..435b822c841e 100644 --- a/include/linux/pci-pwrctrl.h +++ b/include/linux/pci-pwrctrl.h @@ -31,6 +31,8 @@ struct device_link; /** * struct pci_pwrctrl - PCI device power control context. * @dev: Address of the power controlling device. + * @power_on: Callback to power on the power controlling device. + * @power_off: Callback to power off the power controlling device. * * An object of this type must be allocated by the PCI power control device and * passed to the pwrctrl subsystem to trigger a bus rescan and setup a device @@ -38,6 +40,8 @@ struct device_link; */ struct pci_pwrctrl { struct device *dev; + int (*power_on)(struct pci_pwrctrl *pwrctrl); + int (*power_off)(struct pci_pwrctrl *pwrctrl); /* private: internal use only */ struct notifier_block nb; -- cgit v1.2.3 From 4c413248920106393b35b5e014e6ac525405437e Mon Sep 17 00:00:00 2001 From: Krishna Chaitanya Chundru Date: Thu, 15 Jan 2026 12:59:02 +0530 Subject: PCI/pwrctrl: Add APIs to create, destroy pwrctrl devices Previously, the PCI core created pwrctrl devices during pci_scan_device() on its own and then skipped enumeration of those devices, hoping the pwrctrl driver would power them on and trigger a bus rescan. This approach works for endpoint devices directly connected to Root Ports, but it fails for PCIe switches acting as bus extenders. When the switch requires pwrctrl support and the pwrctrl driver is not available during the pwrctrl device creation, its enumeration will be skipped during the initial PCI bus scan. This premature scan leads the PCI core to allocate resources (bridge windows, bus numbers) for the upstream bridge based on available downstream buses at scan time. For non-hotplug capable bridges, PCI core typically allocates resources based on the number of buses available during the initial bus scan, which happens to be just one if the switch is not powered on and enumerated at that time. When the switch gets enumerated later on, it will fail due to the lack of upstream resources. As a result, a PCIe switch powered on by the pwrctrl driver cannot be reliably enumerated currently. Either the switch has to be enabled in the bootloader or the switch pwrctrl driver has to be loaded during the pwrctrl device creation time to work around these issues. Introduce new APIs to explicitly create and destroy pwrctrl devices from controller drivers by recursively scanning the PCI child nodes of the controller. These APIs allow creating pwrctrl devices based on the original criteria and are intended to be called during controller probe and removal. These APIs, together with the upcoming APIs for power on/off will allow the controller drivers to power on all the devices before starting the initial bus scan, thereby solving the resource allocation issue. Signed-off-by: Krishna Chaitanya Chundru [mani: splitted the patch, cleaned up the code, and rewrote description] Signed-off-by: Manivannan Sadhasivam Signed-off-by: Bjorn Helgaas Tested-by: Chen-Yu Tsai Reviewed-by: Bartosz Golaszewski Link: https://patch.msgid.link/20260115-pci-pwrctrl-rework-v5-10-9d26da3ce903@oss.qualcomm.com --- include/linux/pci-pwrctrl.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'include/linux/pci-pwrctrl.h') diff --git a/include/linux/pci-pwrctrl.h b/include/linux/pci-pwrctrl.h index 435b822c841e..44f66872d090 100644 --- a/include/linux/pci-pwrctrl.h +++ b/include/linux/pci-pwrctrl.h @@ -54,5 +54,11 @@ int pci_pwrctrl_device_set_ready(struct pci_pwrctrl *pwrctrl); void pci_pwrctrl_device_unset_ready(struct pci_pwrctrl *pwrctrl); int devm_pci_pwrctrl_device_set_ready(struct device *dev, struct pci_pwrctrl *pwrctrl); - +#if IS_ENABLED(CONFIG_PCI_PWRCTRL) +int pci_pwrctrl_create_devices(struct device *parent); +void pci_pwrctrl_destroy_devices(struct device *parent); +#else +static inline int pci_pwrctrl_create_devices(struct device *parent) { return 0; } +static void pci_pwrctrl_destroy_devices(struct device *parent) { } +#endif #endif /* __PCI_PWRCTRL_H__ */ -- cgit v1.2.3 From b35cf3b6aa1eb08909f58c2d1e2f8ef7d000809a Mon Sep 17 00:00:00 2001 From: Manivannan Sadhasivam Date: Thu, 15 Jan 2026 12:59:03 +0530 Subject: PCI/pwrctrl: Add APIs to power on/off pwrctrl devices To fix bridge resource allocation issues when powering PCI bridges with the pwrctrl driver, introduce APIs to explicitly power on and off all related devices simultaneously. Previously, the individual pwrctrl drivers powered on/off the PCI devices autonomously, without any control from the controller drivers. But to enforce ordering with respect to powering on the devices, these APIs will power on/off all the devices at the same time. The pci_pwrctrl_power_on_devices() API recursively scans the PCI child nodes, makes sure that pwrctrl drivers are bound to devices, and calls their power_on() callbacks. If any pwrctrl driver is not bound, it will return -EPROBE_DEFER. Similarly, pci_pwrctrl_power_off_devices() API powers off devices recursively via their power_off() callbacks. These APIs are expected to be called during the controller probe and suspend/resume time to power on/off the devices. But before calling these APIs, the pwrctrl devices should be created using the pci_pwrctrl_{create/destroy}_devices() APIs. Co-developed-by: Krishna Chaitanya Chundru Signed-off-by: Krishna Chaitanya Chundru Signed-off-by: Manivannan Sadhasivam Signed-off-by: Bjorn Helgaas Tested-by: Chen-Yu Tsai Reviewed-by: Bartosz Golaszewski Link: https://patch.msgid.link/20260115-pci-pwrctrl-rework-v5-11-9d26da3ce903@oss.qualcomm.com --- include/linux/pci-pwrctrl.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/pci-pwrctrl.h') diff --git a/include/linux/pci-pwrctrl.h b/include/linux/pci-pwrctrl.h index 44f66872d090..1192a2527521 100644 --- a/include/linux/pci-pwrctrl.h +++ b/include/linux/pci-pwrctrl.h @@ -57,8 +57,12 @@ int devm_pci_pwrctrl_device_set_ready(struct device *dev, #if IS_ENABLED(CONFIG_PCI_PWRCTRL) int pci_pwrctrl_create_devices(struct device *parent); void pci_pwrctrl_destroy_devices(struct device *parent); +int pci_pwrctrl_power_on_devices(struct device *parent); +void pci_pwrctrl_power_off_devices(struct device *parent); #else static inline int pci_pwrctrl_create_devices(struct device *parent) { return 0; } static void pci_pwrctrl_destroy_devices(struct device *parent) { } +static inline int pci_pwrctrl_power_on_devices(struct device *parent) { return 0; } +static void pci_pwrctrl_power_off_devices(struct device *parent) { } #endif #endif /* __PCI_PWRCTRL_H__ */ -- cgit v1.2.3