linux-kernel - Re: [PATCH 1/2] scsi: ufs: Protect some contexts from unexpected clock scaling

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Date:   Thu, 10 Dec 2020 18:34:49 +0100
From:   Bean Huo <huobean@...il.com>
To:     Can Guo <cang@...eaurora.org>, asutoshd@...eaurora.org,
        nguyenb@...eaurora.org, hongwus@...eaurora.org,
        rnayak@...eaurora.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com, saravanak@...gle.com, salyzyn@...gle.com
Cc:     Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Bart Van Assche <bvanassche@....org>,
        Satya Tangirala <satyat@...gle.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] scsi: ufs: Protect some contexts from unexpected
 clock scaling

Hi Can

On Wed, 2020-12-09 at 05:35 -0800, Can Guo wrote:
> 
>  
> @@ -1160,6 +1166,7 @@ static void
> ufshcd_clock_scaling_unprepare(struct ufs_hba *hba)
>  {
>  	up_write(&hba->clk_scaling_lock);
>  	ufshcd_scsi_unblock_requests(hba);
> +	ufshcd_release(hba);
>  }
>  
>  /**
> @@ -1175,12 +1182,9 @@ static int ufshcd_devfreq_scale(struct ufs_hba
> *hba, bool scale_up)
>  {
>  	int ret = 0;
>  
> -	/* let's not get into low power until clock scaling is
> completed */
> -	ufshcd_hold(hba, false);
> -
>  	ret = ufshcd_clock_scaling_prepare(hba);
>  	if (ret)
> -		goto out;
> +		return ret;
>  
>  	/* scale down the gear before scaling down clocks */
>  	if (!scale_up) {
> @@ -1212,8 +1216,6 @@ static int ufshcd_devfreq_scale(struct ufs_hba
> *hba, bool scale_up)
>  
>  out_unprepare:
>  	ufshcd_clock_scaling_unprepare(hba);
> -out:
> -	ufshcd_release(hba);
>  	return ret;
>  }

I didn't understand why moving ufshcd_hold/ufshcd_release into
ufshcd_clock_scaling_prepare()/ufshcd_clock_scaling_unprepare().


>  
> @@ -1294,15 +1296,8 @@ static int ufshcd_devfreq_target(struct device
> *dev,
>  	}
>  	spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
>  
> -	pm_runtime_get_noresume(hba->dev);
> -	if (!pm_runtime_active(hba->dev)) {
> -		pm_runtime_put_noidle(hba->dev);
> -		ret = -EAGAIN;
> -		goto out;
> -	}
>  	start = ktime_get();
>  	ret = ufshcd_devfreq_scale(hba, scale_up);
> -	pm_runtime_put(hba->dev);
>  

which branch are you working on?  I didn't see this part codes in the
branch 5.11/scsi-queue and 5.11/scsi-staging.

Bean