Re: [PATCH v2 1/1] scsi: ufs: make UFS Tx lane1 clock optional for QCOM platforms

[cang]

Hi Doug,

On 2018-10-12 04:21, Doug Anderson wrote:
> Hi,
>
> On Thu, Oct 11, 2018 at 5:33 AM Can Guo <cang@xxxxxxxxxxxxxx> wrote:
> >  static int ufs_qcom_host_clk_get(struct device *dev,
> > -               const char *name, struct clk **clk_out)
> > +               const char *name, struct clk **clk_out, bool optional)
> >  {
> >         struct clk *clk;
> >         int err = 0;
> >
> >         clk = devm_clk_get(dev, name);
> > -       if (IS_ERR(clk)) {
> > +       if (clk == ERR_PTR(-EPROBE_DEFER)) {
> > +               err = -EPROBE_DEFER;
> > +               dev_warn(dev, "required clock %s hasn't probed yet, 
> > err %d\n",
> > +                               name, err);
> > +       } else if (IS_ERR(clk)) {
> > +               if (optional)
> > +                       return 0;
>
> Change this function to:
>
> static int ufs_qcom_host_clk_get(struct device *dev,
>     const char *name, struct clk **clk_out, bool optional)
> {
>   struct clk *clk;
>   int err;
>
>   clk = devm_clk_get(dev, name);
>   if (!IS_ERR(clk)) {
>     *clk_out = clk;
>     return 0;
>   }
>
>   err = PTR_ERR(clk);
>
>   if (optional && err == -ENOENT) {
>     *clk_out = NULL;
>     return 0;
>   }
>
>   if (err != -EPROBE_DEFER)
>     dev_err(dev, "failed to get %s err %d",
>         name, err);
>
>   return err;
> }
>
> Specifically:
>
> * Typically it just spams the log to print something when you see an
> -EPROBE_DEFER.
>
> * If a clock is optional you should only consider things a success
> only if "-ENOENT" was returned.  All other errors should be considered
> fatal.
>
> * If a clock is optional it's slightly cleaner to set *clk_out to
> NULL.  I know you're initting global data that happened to already be
> NULL by default, but it still feels nice for the abstraction of the
> function to do this.
>
> * Please don't pass __func__ to your error messages.

Thank you for the detailed instructions. Shall make the change like so.

> >                 err = PTR_ERR(clk);
> >                 dev_err(dev, "%s: failed to get %s err %d",
> >                                 __func__, name, err);
> > @@ -113,10 +119,10 @@ static void ufs_qcom_disable_lane_clks(struct 
> > ufs_qcom_host *host)
> >         if (!host->is_lane_clks_enabled)
> >                 return;
> >
> > -       if (host->hba->lanes_per_direction > 1)
> > +       if (host->tx_l1_sync_clk)
>
> Remove this "if".  Always call clk_disable_unprepare() which will be a
> no-op if "host->tx_l1_sync_clk" is NULL.  clk_disable_unprepare() is a
> no-op for NULL clocks by design specifically to make code like this
> cleaner.

Shall do.

> >                 clk_disable_unprepare(host->tx_l1_sync_clk);
> >         clk_disable_unprepare(host->tx_l0_sync_clk);
> > -       if (host->hba->lanes_per_direction > 1)
> > +       if (host->rx_l1_sync_clk)
>
> Remove this "if".  Always call clk_disable_unprepare() which will be a
> no-op if "host->rx_l1_sync_clk" is NULL.  clk_disable_unprepare() is a
> no-op for NULL clocks by design specifically to make code like this
> cleaner.

Shall do.

> >                 clk_disable_unprepare(host->rx_l1_sync_clk);
> >         clk_disable_unprepare(host->rx_l0_sync_clk);
> >
> > @@ -141,12 +147,14 @@ static int ufs_qcom_enable_lane_clks(struct 
> > ufs_qcom_host *host)
> >         if (err)
> >                 goto disable_rx_l0;
> >
> > -       if (host->hba->lanes_per_direction > 1) {
> > +       if (host->rx_l1_sync_clk) {
>
> Remove this "if".  Always call ufs_qcom_host_clk_enable().  The
> clk_prepare_enable() inside ufs_qcom_host_clk_enable() will be a no-op
> if "host->rx_l1_sync_clk" is NULL and will return 0 (no error).

Shall do so.

> >                 err = ufs_qcom_host_clk_enable(dev, 
> > "rx_lane1_sync_clk",
> >                         host->rx_l1_sync_clk);
> >                 if (err)
> >                         goto disable_tx_l0;
> > +       }
> >
> > +       if (host->tx_l1_sync_clk) {
>
> Remove this "if".  Always call ufs_qcom_host_clk_enable().  The
> clk_prepare_enable() inside ufs_qcom_host_clk_enable() will be a no-op
> if "host->tx_l1_sync_clk" is NULL and will return 0 (no error).
>
>
> -Doug

Shall do so. Thank you.

-Can Guo