[PATCH v1 2/3] ufs: core: fix abnormal scale up after last cmd finish

[peter.wang at mediatek.com]

From: Peter Wang <peter.wang at mediatek.com>

When ufshcd_clk_scaling_suspend_work(Thread A) running and new command
coming, ufshcd_clk_scaling_start_busy(Thread B) may get host_lock
after Thread A first time release host_lock. Then Thread A second time
get host_lock will set clk_scaling.window_start_t = 0 which scale up
clock abnormal next polling_ms time.

Below is racing step:
1	hba->clk_scaling.suspend_work (Thread A)
	ufshcd_clk_scaling_suspend_work
2		spin_lock_irqsave(hba->host->host_lock, irq_flags);
3		hba->clk_scaling.is_suspended = true;
4		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
		__ufshcd_suspend_clkscaling
7			spin_lock_irqsave(hba->host->host_lock, flags);
8			hba->clk_scaling.window_start_t = 0;
9			spin_unlock_irqrestore(hba->host->host_lock, flags);

	ufshcd_send_command (Thread B)
		ufshcd_clk_scaling_start_busy
5			spin_lock_irqsave(hba->host->host_lock, flags);
			....
6			spin_unlock_irqrestore(hba->host->host_lock, flags);

Signed-off-by: Peter Wang <peter.wang at mediatek.com>
---
 drivers/ufs/core/ufshcd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index e3672e55efae..017f32b3a789 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -1385,9 +1385,10 @@ static void ufshcd_clk_scaling_suspend_work(struct work_struct *work)
 		return;
 	}
 	hba->clk_scaling.is_suspended = true;
+	hba->clk_scaling.window_start_t = 0;
 	spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
 
-	__ufshcd_suspend_clkscaling(hba);
+	devfreq_suspend_device(hba->devfreq);
 }
 
 static void ufshcd_clk_scaling_resume_work(struct work_struct *work)
-- 
2.18.0