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SubjectRe: [PATCH v2 1/1] scsi: ufs: make UFS Tx lane1 clock optional for QCOM platforms
Hi Doug,

On 2018-10-12 04:21, Doug Anderson wrote:
> Hi,
>
> On Thu, Oct 11, 2018 at 5:33 AM Can Guo <cang@codeaurora.org> 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

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