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Per > both debugfs clk/emc/clk_rate and bpmp/debug/clk/emc/rate. I don't > even see 250MHz as an option. Debugfs emc/available_rates lists 204MHz > as the closest entry. > > I'm trying to think what could cause a drop in the selected clock > rate. This patch should only dynamically change the rate if the opp > tables exist, enabling the cpufreq based scaling via icc. But those > tables don't exist on linux-next right now. My test ramdisk does > nothing except set up sysfs/procfs/etc just enough to run a busybox > shell for debugging. Do the Nvidia regression testing boot scripts do > anything to sysfs or debugfs that would affect emc? So this is definitely coming from ICC. On boot I see a request for 250MHz coming from the PCIe driver ... [ 13.861227] tegra186_emc_icc_set_bw-356: rate 250000000 [ 13.861350] CPU: 1 UID: 0 PID: 68 Comm: kworker/u32:1 Not tainted 6.18.0-rc4-next-20251110-00001-gfc12493c80fb-dirty #9 PREEMPT [ 13.861362] Hardware name: NVIDIA Jetson AGX Xavier Developer Kit (DT) [ 13.861370] Workqueue: events_unbound deferred_probe_work_func [ 13.861388] Call trace: [ 13.861393] show_stack+0x18/0x24 (C) [ 13.861407] dump_stack_lvl+0x74/0x8c [ 13.861419] dump_stack+0x18/0x24 [ 13.861426] tegra186_emc_icc_set_bw+0xc8/0x14c [ 13.861438] apply_constraints+0x70/0xb0 [ 13.861451] icc_set_bw+0x88/0x128 [ 13.861461] tegra_pcie_icc_set+0x7c/0x10c [pcie_tegra194] [ 13.861499] tegra_pcie_dw_start_link+0x178/0x2b0 [pcie_tegra194] [ 13.861510] dw_pcie_host_init+0x664/0x6e0 [ 13.861523] tegra_pcie_dw_probe+0x6d4/0xbfc [pcie_tegra194] [ 13.861534] platform_probe+0x5c/0x98 [ 13.861547] really_probe+0xbc/0x2a8 [ 13.861555] __driver_probe_device+0x78/0x12c [ 13.861563] driver_probe_device+0x3c/0x15c [ 13.861572] __device_attach_driver+0xb8/0x134 [ 13.861580] bus_for_each_drv+0x84/0xe0 [ 13.861588] __device_attach+0x9c/0x188 [ 13.861596] device_initial_probe+0x14/0x20 [ 13.861610] bus_probe_device+0xac/0xb0 [ 13.861619] deferred_probe_work_func+0x88/0xc0 [ 13.861627] process_one_work+0x148/0x28c [ 13.861640] worker_thread+0x2d0/0x3d8 [ 13.861648] kthread+0x128/0x200 [ 13.861659] ret_from_fork+0x10/0x20 The actual rate that is set is 408MHz if I read the rate after it is set ... [ 13.912099] tegra186_emc_icc_set_bw-362: rate 408000000 This is a simple boot test and so nothing we are doing via debugfs/sysfs to influence this. Jon -- nvpublic