Hi Hsin-Yi, I'll get this addressed in the next re-spin which I plan to post by end of this week. On 7/8/19 8:58 AM, Hsin-Yi Wang wrote:
On Thu, Mar 28, 2019 at 3:28 PM Sibi Sankar <sibis@xxxxxxxxxxxxxx> wrote:+ +/* The caller must call dev_pm_opp_put() after the OPP is used */ +struct dev_pm_opp *dev_pm_opp_find_opp_of_np(struct opp_table *opp_table, + struct device_node *opp_np) +{ + return _find_opp_of_np(opp_table, opp_np); +}Hi Sibi, Though this is not the latest version, we've seen following issue: We would get lockdep warnings on this: [ 79.068957] Call trace: [ 79.071396] _find_opp_of_np+0xa0/0xa8 [ 79.075136] dev_pm_opp_find_opp_of_np+0x24/0x30 [ 79.079744] devfreq_passive_event_handler+0x304/0x51c [ 79.084872] devfreq_add_device+0x368/0x434 [ 79.089046] devm_devfreq_add_device+0x68/0xb0 [ 79.093480] mtk_cci_devfreq_probe+0x108/0x158 [ 79.097915] platform_drv_probe+0x80/0xb0 [ 79.101915] really_probe+0x1b4/0x28c [ 79.105568] driver_probe_device+0x64/0xfc [ 79.109655] __driver_attach+0x94/0xcc [ 79.113395] bus_for_each_dev+0x84/0xcc [ 79.117221] driver_attach+0x2c/0x38 [ 79.120788] bus_add_driver+0x120/0x1f4 [ 79.124614] driver_register+0x64/0xf8 [ 79.128355] __platform_driver_register+0x4c/0x58 [ 79.133049] mtk_cci_devfreq_init+0x1c/0x24 [ 79.137224] do_one_initcall+0x1c0/0x3e0 [ 79.141138] do_initcall_level+0x1f4/0x224 [ 79.145225] do_basic_setup+0x34/0x4c [ 79.148878] kernel_init_freeable+0x10c/0x194 [ 79.153225] kernel_init+0x14/0x100 [ 79.156705] ret_from_fork+0x10/0x18 [ 79.160270] irq event stamp: 238006 [ 79.163750] hardirqs last enabled at (238005): [<ffffffa71fdea0a4>] _raw_spin_unlock_irqrestore+0x40/0x84 [ 79.173391] hardirqs last disabled at (238006): [<ffffffa71f480e78>] do_debug_exception+0x70/0x198 [ 79.182337] softirqs last enabled at (237998): [<ffffffa71f48165c>] __do_softirq+0x45c/0x4a4 [ 79.190850] softirqs last disabled at (237987): [<ffffffa71f4bc0d4>] irq_exit+0xd8/0xf8 [ 79.198842] ---[ end trace 0e66a55077a0abab ]--- In _find_opp_of_np()[1], there's lockdep_assert_held(&opp_table_lock); [1] https://elixir.bootlin.com/linux/latest/source/drivers/opp/of.c#L75 But in governor passive.c#cpufreq_passive_register(), it call dev_pm_opp_find_opp_of_np() directly, so it wouldn't access opp_table_lock lock. Another similar place is in dev_pm_opp_of_add_table(), most devfreq would call this to get opp table. dev_pm_opp_of_add_table --> _opp_add_static_v2 --> _of_opp_alloc_required_opps // would goes here if opp table contains "required-opps" property. --> _find_opp_of_np cpufreq-map governor needs devfreq to have "required-opps" property. So it would also trigger above lockdep warning. The question is: Is lockdep_assert_held(&opp_table_lock); needed in above use cases? Since they don't need to modify device and opp lists. Thanks
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