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There are should > > other problems if interfere each others. > > > > terminate should wait issue_pending finish and block queue new request. > > Both pl330_issue_pending() and pl330_terminate_all() already use > pch->lock to protect the channel state. However, issue_pending() > also invokes pl330_tasklet() after releasing the lock, so this > does not establish complete synchronization. > > I ran a source-based interleaving test. The original > code reproduces the extra runtime PM put after termination, while > the proposed one-line fix balances the references under the same > interleaving. > > > This function can be called in an interrupt context > > > > call pm_runtime_get() is risk, which may sleep. > > pl330_probe() calls pm_runtime_irq_safe(&adev->dev), and the AMBA > runtime PM callbacks use clk_enable()/clk_disable() for IRQ-safe > devices. This allows pm_runtime_get_sync() to be called from > atomic context, provided the relevant PM callbacks and dependencies > satisfy the IRQ-safe requirements. > > I agree that the remaining synchronization and error-handling > paths deserve further investigation. > > Would it be reasonable to keep this patch focused on the > reproduced reference-count imbalance and address any confirmed > synchronization issues separately? This is quick fix after I read code again. but original mothed is not good enough, which mix use check varible and runtime_pm reference-count. If pair get() and put(), needn't pch->active. if (list_empty(&pch->work_list)) { /* * Warn on nothing pending. Empty submitted_list may * break our pm_runtime usage counter as it is * updated on work_list emptiness status. */ WARN_ON(list_empty(&pch->submitted_list)); pch->active = true; pm_runtime_get_sync(pch->dmac->ddma.dev); } simple call for_each(work_list) { pm_runtime_get_sync() } ideally, there are PM API (pm_runtime_get_sync(, count(work_list)) to bump more than 1 ref count. But you can use above code to proof concept. In pl330_tasklet() while (!list_empty(&pch->completed_list)) { ... pm_runtime_put_autosuspend() } Keep pm ref count is the same as count of work_list. So needn't pch->active at all. Frank > > Thanks, > Mizuno