Problem: Some of our machines are configured with many NVMe devices and are validated for strict shutdown time requirements. Each NVMe device plugged into the system, typicaly takes about 4.5 secs to shutdown. A system with 16 such NVMe devices will takes approximately 80 secs to shutdown and go through reboot. The current shutdown APIs as defined at bus level is defined to be synchronous. Therefore, more devices are in the system the greater the time it takes to shutdown. This shutdown time significantly contributes the machine reboot time. Solution: This patch set proposes an asynchronous shutdown interface at bus level, modifies the core driver, device shutdown routine to exploit the new interface while maintaining backward compatibility with synchronous implementation already existing (Patch 1 of 3) and exploits new interface to enable all PCI-E based devices to use asynchronous interface semantics if necessary (Patch 2 of 3). The implementation at PCI-E level also works in a backward compatible way, to allow exiting device implementation to work with current synchronous semantics. Only show cases an example implementation for NVMe device to exploit this asynchronous shutdown interface. (Patch 3 of 3). Changelog: v2: - Replaced the shutdown_pre & shutdown_post entry point names with the recommended names (async_shutdown_start and asynch_shutdown_end). - Comment about ordering requirements between bridge shutdown versus leaf/endpoint shutdown was agreed to be different when calling async_shutdown_start and async_shutdown_end. Now this implements the same order of calling both start and end entry points. Tanjore Suresh (3): driver core: Support asynchronous driver shutdown PCI: Support asynchronous shutdown nvme: Add async shutdown support drivers/base/core.c | 38 +++++++++++++++++- drivers/nvme/host/core.c | 28 +++++++++---- drivers/nvme/host/nvme.h | 8 ++++ drivers/nvme/host/pci.c | 80 ++++++++++++++++++++++++-------------- drivers/pci/pci-driver.c | 20 ++++++++-- include/linux/device/bus.h | 12 ++++++ include/linux/pci.h | 4 ++ 7 files changed, 149 insertions(+), 41 deletions(-) -- 2.36.0.rc0.470.gd361397f0d-goog