Hello, I'm a hardware guy, debugging an embedded system using a Cyclone V SOC. It utilizes pcie 1.0 with four lanes connected to an NVMe drive for main storage. Bringup has come to a halt as I haven't been able to get the altera-pci driver to play nice with the nvme driver. The altera-pcie module loads and lspci -v shows the nvme drive and the number of lanes connected and speed, but when I load the nvme driver it hangs on the first try: (pardon my printk's, I've been trying to track this down to find out what I'm doing wrong in the hardware) nvme: Successfully exiting nvme_pci_enable. pci.c: nvme_reset_work: calling nvme_pci_configure_admin_queue. nvme: core.c: nvme_wait_ready entry nvme: core.c: nvme_wait_ready return nvme: core.c: nvme_wait_ready entry nvme: core.c: nvme_wait_ready return pci.c: nvme_reset_work: calling nvme_alloc_admin_tags. nvme: core.c: nvme_change_ctrl_state entry pci.c: nvme_reset_work: calling nvme_init_identify. nvme: core.c: entering nvme_init_identify nvme: core.c: nvme_init_identify: calling nvme_identify_ctrl nvme: core.c: Entering nvme_identify_ctrl nvme: core.c: nvme_identify_ctrl: getting nvme_admin_identify... nvme: core.c: nvme_identify_ctrl: kmalloc(nvme_id_ctrl) nvme: core.c: nvme_identify_ctrl: calling nvme_submit_sync_cmd nvme: core.c: Entering __nvme_submit_sync_cmd nvme: core.c: __nvme_submit_sync_cmd: calling nvme_alloc_request nvme: core.c: nvme_alloc_request entry nvme: core.c: nvme_alloc_request calling blk_mq_alloc_request nvme: core.c: nvme_alloc_request done. cmd = 0xef22fd08 nvme: core.c: __nvme_submit_sync_cmd: calling blk_rq_map_kern nvme: core.c: __nvme_submit_sync_cmd: calling blk_execute_rq blk-exec.c: Entering blk_execute_rq blk-exec.c: blk_execute_rq: calling blk_execute_rq_nowait blk-exec.c: blk_execute_rq_nowait: calling blk_mq_sched_insert_request nvme: core.c: nvme_setup_cmd entry nvme: core.c: nvme_setup_cmd: adding command: 34 to nvme_req queue nvme: core.c: nvme_setup_cmd return blk-exec.c: blk_execute_rq: starting wait_for_completion_io_timeout() After a watchdog, reboot and reload of both modules, it produces this message sometimes other times it repeats the watchdog reset: [ 64.471966] nvme nvme0: I/O 16 QID 0 timeout, disable controller [ 64.478147] nvme nvme0: Identify Controller failed (-4) [ 64.483380] nvme nvme0: Removing after probe failure status: -5 According to my printks the nvme driver is attempting a drive identify. But the blk read never returns. I can't figure out exactly what code is being called by the nvme driver as none of the altera-pci routine printks I have installed are showing up before the hang. The code traverses into blk-exec.c and never comes out. I know it's a big ask, but can someone advise me on how to proceed to debug this? Brian
