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

[Bart Van Assche]

On 8/23/23 02:29, peter.wang at mediatek.com wrote:
> 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)

There is a second __ufshcd_suspend_clkscaling() call in the same source
file. Please fix that call too.

Thanks,

Bart.