From b50d9c27a31ed617e2e39787d134f8207d70e5af Mon Sep 17 00:00:00 2001 From: Peter Wang Date: Thu, 31 Aug 2023 21:08:26 +0800 Subject: scsi: ufs: core: Fix abnormal scale up after scale down When no active_reqs, devfreq_monitor (thread A) will suspend clock scaling. But it may have racing with clk_scaling.suspend_work (thread B) and actually not suspend clock scaling (requeue after suspend). Next time after polling_ms, devfreq_monitor read clk_scaling.window_start_t = 0 then scale up clock abnormal. Below is racing step: devfreq->work (Thread A) devfreq_monitor update_devfreq ..... ufshcd_devfreq_target queue_work(hba->clk_scaling.workq, 1 &hba->clk_scaling.suspend_work) ..... 5 queue_delayed_work(devfreq_wq, &devfreq->work, msecs_to_jiffies(devfreq->profile->polling_ms)); 2 hba->clk_scaling.suspend_work (Thread B) ufshcd_clk_scaling_suspend_work __ufshcd_suspend_clkscaling devfreq_suspend_device(hba->devfreq); 3 cancel_delayed_work_sync(&devfreq->work); 4 hba->clk_scaling.window_start_t = 0; ..... Signed-off-by: Peter Wang Link: https://lore.kernel.org/r/20230831130826.5592-4-peter.wang@mediatek.com Reviewed-by: Bart Van Assche Signed-off-by: Martin K. Petersen --- drivers/ufs/core/ufshcd.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'drivers/ufs') diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c index 729f49cfff4c..af576d3606f6 100644 --- a/drivers/ufs/core/ufshcd.c +++ b/drivers/ufs/core/ufshcd.c @@ -1402,6 +1402,13 @@ static int ufshcd_devfreq_target(struct device *dev, return 0; } + /* Skip scaling clock when clock scaling is suspended */ + if (hba->clk_scaling.is_suspended) { + spin_unlock_irqrestore(hba->host->host_lock, irq_flags); + dev_warn(hba->dev, "clock scaling is suspended, skip"); + return 0; + } + if (!hba->clk_scaling.active_reqs) sched_clk_scaling_suspend_work = true; -- cgit v1.2.3