diff mbox series

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

Message ID 1539261196-14550-1-git-send-email-cang@codeaurora.org (mailing list archive)
State Not Applicable, archived
Delegated to: Andy Gross
Headers show
Series [v2,1/1] scsi: ufs: make UFS Tx lane1 clock optional for QCOM platforms | expand

Commit Message

Can Guo Oct. 11, 2018, 12:33 p.m. UTC 
From: Venkat Gopalakrishnan <venkatg@codeaurora.org>

Per Qcom's UFS host controller HW design, the UFS Tx lane1 clock could be
muxed with Tx lane0 clock, hence keep Tx lane1 clock optional by ignoring
it if it is not provided in device tree. This change also performs some
cleanup to lanes per direction checks when enable/disable lane clocks just
for symmetry.

Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
---

Changes since v1:
- Incorporated review comments from Doug.
- Update the commit title and commit message.

 drivers/scsi/ufs/ufs-qcom.c | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

Comments

Doug Anderson Oct. 11, 2018, 8:21 p.m. UTC | #1 
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.


>                 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.


>                 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.


>                 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).


>                 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
Can Guo Oct. 12, 2018, 12:55 a.m. UTC | #2 
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
diff mbox series

Patch

diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index 2b38db2..a7ec959 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -79,13 +79,19 @@  static int ufs_qcom_get_connected_tx_lanes(struct ufs_hba *hba, u32 *tx_lanes)
 }
 
 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;
 		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)
 		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)
 		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) {
 		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) {
 		err = ufs_qcom_host_clk_enable(dev, "tx_lane1_sync_clk",
 			host->tx_l1_sync_clk);
 		if (err)
@@ -157,8 +165,7 @@  static int ufs_qcom_enable_lane_clks(struct ufs_qcom_host *host)
 	goto out;
 
 disable_rx_l1:
-	if (host->hba->lanes_per_direction > 1)
-		clk_disable_unprepare(host->rx_l1_sync_clk);
+	clk_disable_unprepare(host->rx_l1_sync_clk);
 disable_tx_l0:
 	clk_disable_unprepare(host->tx_l0_sync_clk);
 disable_rx_l0:
@@ -172,25 +179,25 @@  static int ufs_qcom_init_lane_clks(struct ufs_qcom_host *host)
 	int err = 0;
 	struct device *dev = host->hba->dev;
 
-	err = ufs_qcom_host_clk_get(dev,
-			"rx_lane0_sync_clk", &host->rx_l0_sync_clk);
+	err = ufs_qcom_host_clk_get(dev, "rx_lane0_sync_clk",
+					&host->rx_l0_sync_clk, false);
 	if (err)
 		goto out;
 
-	err = ufs_qcom_host_clk_get(dev,
-			"tx_lane0_sync_clk", &host->tx_l0_sync_clk);
+	err = ufs_qcom_host_clk_get(dev, "tx_lane0_sync_clk",
+					&host->tx_l0_sync_clk, false);
 	if (err)
 		goto out;
 
 	/* In case of single lane per direction, don't read lane1 clocks */
 	if (host->hba->lanes_per_direction > 1) {
 		err = ufs_qcom_host_clk_get(dev, "rx_lane1_sync_clk",
-			&host->rx_l1_sync_clk);
+			&host->rx_l1_sync_clk, false);
 		if (err)
 			goto out;
 
 		err = ufs_qcom_host_clk_get(dev, "tx_lane1_sync_clk",
-			&host->tx_l1_sync_clk);
+			&host->tx_l1_sync_clk, true);
 	}
 out:
 	return err;