linux-kernel - Re: [PATCH v2 2/2] scsi: ufs: Use freq table with devfreq

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Date:   Wed, 16 May 2018 14:20:33 -0700
From:   Subhash Jadavani <subhashj@...eaurora.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Vinayak Holikatti <vinholikatti@...il.com>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        linux-scsi@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        linux-scsi-owner@...r.kernel.org
Subject: Re: [PATCH v2 2/2] scsi: ufs: Use freq table with devfreq

On 2018-05-04 15:44, Bjorn Andersson wrote:
> devfreq requires that the client operates on actual frequencies, not
> only 0 and UMAX_INT and as such UFS brok with the introduction of
> f1d981eaecf8 ("PM / devfreq: Use the available min/max frequency").
> 
> This patch registers the frequencies of the first clock as opp levels
> and use these to determine if we're trying to step up or down.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
> 
> Chances since v1:
> - Register min_freq and max_freq as opp levels.
> - Unregister opp levels on removal, to make e.g. probe defer working
> 
>  drivers/scsi/ufs/ufshcd.c | 47 +++++++++++++++++++++++++++++++++------
>  1 file changed, 40 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 2253f24309ec..257614b889bd 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -1168,16 +1168,13 @@ static int ufshcd_devfreq_target(struct device 
> *dev,
>  	struct ufs_hba *hba = dev_get_drvdata(dev);
>  	ktime_t start;
>  	bool scale_up, sched_clk_scaling_suspend_work = false;
> +	struct list_head *clk_list = &hba->clk_list_head;
> +	struct ufs_clk_info *clki;
>  	unsigned long irq_flags;
> 
>  	if (!ufshcd_is_clkscaling_supported(hba))
>  		return -EINVAL;
> 
> -	if ((*freq > 0) && (*freq < UINT_MAX)) {
> -		dev_err(hba->dev, "%s: invalid freq = %lu\n", __func__, *freq);
> -		return -EINVAL;
> -	}
> -
>  	spin_lock_irqsave(hba->host->host_lock, irq_flags);
>  	if (ufshcd_eh_in_progress(hba)) {
>  		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
> @@ -1187,7 +1184,13 @@ static int ufshcd_devfreq_target(struct device 
> *dev,
>  	if (!hba->clk_scaling.active_reqs)
>  		sched_clk_scaling_suspend_work = true;
> 
> -	scale_up = (*freq == UINT_MAX) ? true : false;
> +	if (list_empty(clk_list)) {
> +		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
> +		goto out;
> +	}
> +
> +	clki = list_first_entry(clk_list, struct ufs_clk_info, list);
> +	scale_up = (*freq == clki->max_freq) ? true : false;
>  	if (!ufshcd_is_devfreq_scaling_required(hba, scale_up)) {
>  		spin_unlock_irqrestore(hba->host->host_lock, irq_flags);
>  		ret = 0;
> @@ -1257,16 +1260,29 @@ static struct devfreq_dev_profile
> ufs_devfreq_profile = {
> 
>  static int ufshcd_devfreq_init(struct ufs_hba *hba)
>  {
> +	struct list_head *clk_list = &hba->clk_list_head;
> +	struct ufs_clk_info *clki;
>  	struct devfreq *devfreq;
>  	int ret;
> 
> -	devfreq = devm_devfreq_add_device(hba->dev,
> +	/* Skip devfreq if we don't have any clocks in the list */
> +	if (list_empty(clk_list))
> +		return 0;
> +
> +	clki = list_first_entry(clk_list, struct ufs_clk_info, list);
> +	dev_pm_opp_add(hba->dev, clki->min_freq, 0);
> +	dev_pm_opp_add(hba->dev, clki->max_freq, 0);
> +
> +	devfreq = devfreq_add_device(hba->dev,
>  			&ufs_devfreq_profile,
>  			"simple_ondemand",
>  			NULL);
>  	if (IS_ERR(devfreq)) {
>  		ret = PTR_ERR(devfreq);
>  		dev_err(hba->dev, "Unable to register with devfreq %d\n", ret);
> +
> +		dev_pm_opp_remove(hba->dev, clki->min_freq);
> +		dev_pm_opp_remove(hba->dev, clki->max_freq);
>  		return ret;
>  	}
> 
> @@ -1275,6 +1291,22 @@ static int ufshcd_devfreq_init(struct ufs_hba 
> *hba)
>  	return 0;
>  }
> 
> +static void ufshcd_devfreq_remove(struct ufs_hba *hba)
> +{
> +	struct list_head *clk_list = &hba->clk_list_head;
> +	struct ufs_clk_info *clki;
> +
> +	if (!hba->devfreq)
> +		return;
> +
> +	devfreq_remove_device(hba->devfreq);
> +	hba->devfreq = NULL;
> +
> +	clki = list_first_entry(clk_list, struct ufs_clk_info, list);
> +	dev_pm_opp_remove(hba->dev, clki->min_freq);
> +	dev_pm_opp_remove(hba->dev, clki->max_freq);
> +}
> +
>  static void __ufshcd_suspend_clkscaling(struct ufs_hba *hba)
>  {
>  	unsigned long flags;
> @@ -6966,6 +6998,7 @@ static void ufshcd_hba_exit(struct ufs_hba *hba)
>  			if (hba->devfreq)
>  				ufshcd_suspend_clkscaling(hba);
>  			destroy_workqueue(hba->clk_scaling.workq);
> +			ufshcd_devfreq_remove(hba);
>  		}
>  		ufshcd_setup_clocks(hba, false);
>  		ufshcd_setup_hba_vreg(hba, false);

Looks good to me.
Reviewed-by: Subhash Jadavani <subhashj@...eaurora.org>

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