RE: [PATCH 1/2] scsi: ufs: Clean up ufshcd_scale_clks() and clock scaling error out path

[Avri Altman]

Hi,

> 
> From: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
> 
> This change introduces a func ufshcd_set_clk_freq() to explicitly
> set clock frequency so that it can be used in reset_and_resotre path and
> in ufshcd_scale_clks(). Meanwhile, this change cleans up the clock scaling
> error out path.
> 
> Signed-off-by: Subhash Jadavani <subhashj@xxxxxxxxxxxxxx>
> Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 2a2a63b..63aaa88f 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -855,28 +855,29 @@ static bool
> ufshcd_is_unipro_pa_params_tuning_req(struct ufs_hba *hba)
>                 return false;
>  }
> 
> -static int ufshcd_scale_clks(struct ufs_hba *hba, bool scale_up)
> +/**
> + * ufshcd_set_clk_freq - set UFS controller clock frequencies
> + * @hba: per adapter instance
> + * @scale_up: If True, set max possible frequency othewise set low
> frequency
> + *
> + * Returns 0 if successful
> + * Returns < 0 for any other errors
> + */
> +static int ufshcd_set_clk_freq(struct ufs_hba *hba, bool scale_up)
Personally I prefer using the convention of "__scale_clks" to describe the privet core of scale_clks,
But I know that many people are against it.

>  {
>         int ret = 0;
>         struct ufs_clk_info *clki;
>         struct list_head *head = &hba->clk_list_head;
> -       ktime_t start = ktime_get();
> -       bool clk_state_changed = false;
> 
>         if (list_empty(head))
>                 goto out;
> 
> -       ret = ufshcd_vops_clk_scale_notify(hba, scale_up, PRE_CHANGE);
> -       if (ret)
> -               return ret;
> -
>         list_for_each_entry(clki, head, list) {
>                 if (!IS_ERR_OR_NULL(clki->clk)) {
>                         if (scale_up && clki->max_freq) {
>                                 if (clki->curr_freq == clki->max_freq)
>                                         continue;
> 
> -                               clk_state_changed = true;
>                                 ret = clk_set_rate(clki->clk, clki->max_freq);
>                                 if (ret) {
>                                         dev_err(hba->dev, "%s: %s clk set rate(%dHz) failed,
> %d\n",
> @@ -895,7 +896,6 @@ static int ufshcd_scale_clks(struct ufs_hba *hba,
> bool scale_up)
>                                 if (clki->curr_freq == clki->min_freq)
>                                         continue;
> 
> -                               clk_state_changed = true;
>                                 ret = clk_set_rate(clki->clk, clki->min_freq);
>                                 if (ret) {
>                                         dev_err(hba->dev, "%s: %s clk set rate(%dHz) failed,
> %d\n",
> @@ -914,13 +914,36 @@ static int ufshcd_scale_clks(struct ufs_hba *hba,
> bool scale_up)
>                                 clki->name, clk_get_rate(clki->clk));
>         }
> 
> +out:
> +       return ret;
> +}
> +
> +/**
> + * ufshcd_scale_clks - scale up or scale down UFS controller clocks
> + * @hba: per adapter instance
> + * @scale_up: True if scaling up and false if scaling down
> + *
> + * Returns 0 if successful
> + * Returns < 0 for any other errors
> + */
> +static int ufshcd_scale_clks(struct ufs_hba *hba, bool scale_up)
> +{
> +       int ret = 0;
> +
> +       ret = ufshcd_vops_clk_scale_notify(hba, scale_up, PRE_CHANGE);
> +       if (ret)
> +               return ret;
> +
> +       ret = ufshcd_set_clk_freq(hba, scale_up);
> +       if (ret)
> +               return ret;
> +
>         ret = ufshcd_vops_clk_scale_notify(hba, scale_up, POST_CHANGE);
> +       if (ret) {
> +               ufshcd_set_clk_freq(hba, !scale_up);
> +               return ret;
> +       }
> 
> -out:
> -       if (clk_state_changed)
> -               trace_ufshcd_profile_clk_scaling(dev_name(hba->dev),
> -                       (scale_up ? "up" : "down"),
> -                       ktime_to_us(ktime_sub(ktime_get(), start)), ret);

Why remove the ufshcd_profile_clk_scaling trace?


>         return ret;
>  }
> 
> @@ -1106,35 +1129,36 @@ static int ufshcd_devfreq_scale(struct ufs_hba
> *hba, bool scale_up)
> 
>         ret = ufshcd_clock_scaling_prepare(hba);
>         if (ret)
> -               return ret;
> +               goto out;
Are you fixing here a hold without release?
Should make note of that.

> 
>         /* scale down the gear before scaling down clocks */
>         if (!scale_up) {
>                 ret = ufshcd_scale_gear(hba, false);
>                 if (ret)
> -                       goto out;
> +                       goto clk_scaling_unprepare;
>         }
> 
>         ret = ufshcd_scale_clks(hba, scale_up);
> -       if (ret) {
> -               if (!scale_up)
> -                       ufshcd_scale_gear(hba, true);
> -               goto out;
> -       }
> +       if (ret)
> +               goto scale_up_gear;
> 
>         /* scale up the gear after scaling up clocks */
>         if (scale_up) {
>                 ret = ufshcd_scale_gear(hba, true);
>                 if (ret) {
>                         ufshcd_scale_clks(hba, false);
> -                       goto out;
> +                       goto clk_scaling_unprepare;
>                 }
>         }
> 
> -       ret = ufshcd_vops_clk_scale_notify(hba, scale_up, POST_CHANGE);
> +       goto clk_scaling_unprepare;
I think you should find a way to make this function more readable.
Adding all those "spaghetti" gotos making it even harder to read. 

Thanks,
Avri

> 
> -out:
> +scale_up_gear:
> +       if (!scale_up)
> +               ufshcd_scale_gear(hba, true);
> +clk_scaling_unprepare:
>         ufshcd_clock_scaling_unprepare(hba);
> +out:
>         ufshcd_release(hba);
>         return ret;
>  }
> @@ -6251,7 +6275,7 @@ static int ufshcd_host_reset_and_restore(struct
> ufs_hba *hba)
>         spin_unlock_irqrestore(hba->host->host_lock, flags);
> 
>         /* scale up clocks to max frequency before full reinitialization */
> -       ufshcd_scale_clks(hba, true);
> +       ufshcd_set_clk_freq(hba, true);
> 
>         err = ufshcd_hba_enable(hba);
>         if (err)
> --
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