1. Patchew
  2. linux
  3. [PATCH V2 0/6] Refactor phy powerup sequence
  4. View patch

[PATCH V2 6/6] scsi: ufs: host : Introduce phy_power_on/off wrapper function

Nitin Rawat posted 6 patches 9 months ago
There is a newer version of this series
[PATCH V2 6/6] scsi: ufs: host : Introduce phy_power_on/off wrapper function
Posted by Nitin Rawat 9 months ago 
Introduce ufs_qcom_phy_power_on and ufs_qcom_phy_power_off wrapper
functions with mutex protection to ensure safe usage of is_phy_pwr_on
and prevent possible race conditions.

Co-developed-by: Can Guo <quic_cang@quicinc.com>
Signed-off-by: Can Guo <quic_cang@quicinc.com>
Signed-off-by: Nitin Rawat <quic_nitirawa@quicinc.com>
---
 drivers/ufs/host/ufs-qcom.c | 44 +++++++++++++++++++++++++++++++------
 drivers/ufs/host/ufs-qcom.h |  4 ++++
 2 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
index 5c7b6c75d669..8f80724e64b9 100644
--- a/drivers/ufs/host/ufs-qcom.c
+++ b/drivers/ufs/host/ufs-qcom.c
@@ -421,6 +421,38 @@ static u32 ufs_qcom_get_hs_gear(struct ufs_hba *hba)
 	return UFS_HS_G3;
 }

+static int ufs_qcom_phy_power_on(struct ufs_hba *hba)
+{
+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
+	struct phy *phy = host->generic_phy;
+	int ret = 0;
+
+	guard(mutex)(&host->phy_mutex);
+	if (!host->is_phy_pwr_on) {
+		ret = phy_power_on(phy);
+		if (!ret)
+			host->is_phy_pwr_on = true;
+	}
+
+	return ret;
+}
+
+static int ufs_qcom_phy_power_off(struct ufs_hba *hba)
+{
+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
+	struct phy *phy = host->generic_phy;
+	int ret = 0;
+
+	guard(mutex)(&host->phy_mutex);
+	if (host->is_phy_pwr_on) {
+		ret = phy_power_off(phy);
+		if (!ret)
+			host->is_phy_pwr_on = false;
+	}
+
+	return ret;
+}
+
 static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
@@ -449,7 +481,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
 		return ret;

 	if (phy->power_count) {
-		phy_power_off(phy);
+		ufs_qcom_phy_power_off(hba);
 		phy_exit(phy);
 	}

@@ -466,7 +498,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
 		goto out_disable_phy;

 	/* power on phy - start serdes and phy's power and clocks */
-	ret = phy_power_on(phy);
+	ret = ufs_qcom_phy_power_on(hba);
 	if (ret) {
 		dev_err(hba->dev, "%s: phy power on failed, ret = %d\n",
 			__func__, ret);
@@ -1017,7 +1049,6 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
 				 enum ufs_notify_change_status status)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
-	struct phy *phy = host->generic_phy;
 	int err;

 	/*
@@ -1037,7 +1068,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
 				/* disable device ref_clk */
 				ufs_qcom_dev_ref_clk_ctrl(host, false);
 			}
-			err = phy_power_off(phy);
+			err = ufs_qcom_phy_power_off(hba);
 			if (err) {
 				dev_err(hba->dev, "phy power off failed, ret=%d\n", err);
 					return err;
@@ -1046,7 +1077,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
 		break;
 	case POST_CHANGE:
 		if (on) {
-			err = phy_power_on(phy);
+			err = ufs_qcom_phy_power_on(hba);
 			if (err) {
 				dev_err(hba->dev, "phy power on failed, ret = %d\n", err);
 				return err;
@@ -1233,10 +1264,9 @@ static int ufs_qcom_init(struct ufs_hba *hba)
 static void ufs_qcom_exit(struct ufs_hba *hba)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
-	struct phy *phy = host->generic_phy;

 	ufs_qcom_disable_lane_clks(host);
-	phy_power_off(phy);
+	ufs_qcom_phy_power_off(hba);
 	phy_exit(host->generic_phy);
 }

diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
index d0e6ec9128e7..3db29fbcd40b 100644
--- a/drivers/ufs/host/ufs-qcom.h
+++ b/drivers/ufs/host/ufs-qcom.h
@@ -252,6 +252,10 @@ struct ufs_qcom_host {
 	u32 phy_gear;

 	bool esi_enabled;
+	/* flag to check if phy is powered on */
+	bool is_phy_pwr_on;
+	/* Protect the usage of is_phy_pwr_on against racing */
+	struct mutex phy_mutex;
 };

 struct ufs_qcom_drvdata {
--
2.48.1
Re: [PATCH V2 6/6] scsi: ufs: host : Introduce phy_power_on/off wrapper function
Posted by Bjorn Andersson 9 months ago 
On Tue, Mar 18, 2025 at 08:19:44PM +0530, Nitin Rawat wrote:
> Introduce ufs_qcom_phy_power_on and ufs_qcom_phy_power_off wrapper
> functions with mutex protection to ensure safe usage of is_phy_pwr_on
> and prevent possible race conditions.
> 

Please describe the problem properly here. Are you introducing the mutex
because there is a problem, or because you want to be "safe"?

Why is it "refcounted", is the calling code paths no longer in sync? How
long has the current implementation been broken?

Regards,
Bjorn

> Co-developed-by: Can Guo <quic_cang@quicinc.com>
> Signed-off-by: Can Guo <quic_cang@quicinc.com>
> Signed-off-by: Nitin Rawat <quic_nitirawa@quicinc.com>
> ---
>  drivers/ufs/host/ufs-qcom.c | 44 +++++++++++++++++++++++++++++++------
>  drivers/ufs/host/ufs-qcom.h |  4 ++++
>  2 files changed, 41 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
> index 5c7b6c75d669..8f80724e64b9 100644
> --- a/drivers/ufs/host/ufs-qcom.c
> +++ b/drivers/ufs/host/ufs-qcom.c
> @@ -421,6 +421,38 @@ static u32 ufs_qcom_get_hs_gear(struct ufs_hba *hba)
>  	return UFS_HS_G3;
>  }
> 
> +static int ufs_qcom_phy_power_on(struct ufs_hba *hba)
> +{
> +	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> +	struct phy *phy = host->generic_phy;
> +	int ret = 0;
> +
> +	guard(mutex)(&host->phy_mutex);
> +	if (!host->is_phy_pwr_on) {
> +		ret = phy_power_on(phy);
> +		if (!ret)
> +			host->is_phy_pwr_on = true;
> +	}
> +
> +	return ret;
> +}
> +
> +static int ufs_qcom_phy_power_off(struct ufs_hba *hba)
> +{
> +	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> +	struct phy *phy = host->generic_phy;
> +	int ret = 0;
> +
> +	guard(mutex)(&host->phy_mutex);
> +	if (host->is_phy_pwr_on) {
> +		ret = phy_power_off(phy);
> +		if (!ret)
> +			host->is_phy_pwr_on = false;
> +	}
> +
> +	return ret;
> +}
> +
>  static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
>  {
>  	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> @@ -449,7 +481,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
>  		return ret;
> 
>  	if (phy->power_count) {
> -		phy_power_off(phy);
> +		ufs_qcom_phy_power_off(hba);
>  		phy_exit(phy);
>  	}
> 
> @@ -466,7 +498,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
>  		goto out_disable_phy;
> 
>  	/* power on phy - start serdes and phy's power and clocks */
> -	ret = phy_power_on(phy);
> +	ret = ufs_qcom_phy_power_on(hba);
>  	if (ret) {
>  		dev_err(hba->dev, "%s: phy power on failed, ret = %d\n",
>  			__func__, ret);
> @@ -1017,7 +1049,6 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>  				 enum ufs_notify_change_status status)
>  {
>  	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> -	struct phy *phy = host->generic_phy;
>  	int err;
> 
>  	/*
> @@ -1037,7 +1068,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>  				/* disable device ref_clk */
>  				ufs_qcom_dev_ref_clk_ctrl(host, false);
>  			}
> -			err = phy_power_off(phy);
> +			err = ufs_qcom_phy_power_off(hba);
>  			if (err) {
>  				dev_err(hba->dev, "phy power off failed, ret=%d\n", err);
>  					return err;
> @@ -1046,7 +1077,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>  		break;
>  	case POST_CHANGE:
>  		if (on) {
> -			err = phy_power_on(phy);
> +			err = ufs_qcom_phy_power_on(hba);
>  			if (err) {
>  				dev_err(hba->dev, "phy power on failed, ret = %d\n", err);
>  				return err;
> @@ -1233,10 +1264,9 @@ static int ufs_qcom_init(struct ufs_hba *hba)
>  static void ufs_qcom_exit(struct ufs_hba *hba)
>  {
>  	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
> -	struct phy *phy = host->generic_phy;
> 
>  	ufs_qcom_disable_lane_clks(host);
> -	phy_power_off(phy);
> +	ufs_qcom_phy_power_off(hba);
>  	phy_exit(host->generic_phy);
>  }
> 
> diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
> index d0e6ec9128e7..3db29fbcd40b 100644
> --- a/drivers/ufs/host/ufs-qcom.h
> +++ b/drivers/ufs/host/ufs-qcom.h
> @@ -252,6 +252,10 @@ struct ufs_qcom_host {
>  	u32 phy_gear;
> 
>  	bool esi_enabled;
> +	/* flag to check if phy is powered on */
> +	bool is_phy_pwr_on;
> +	/* Protect the usage of is_phy_pwr_on against racing */
> +	struct mutex phy_mutex;
>  };
> 
>  struct ufs_qcom_drvdata {
> --
> 2.48.1
> 
>
Re: [PATCH V2 6/6] scsi: ufs: host : Introduce phy_power_on/off wrapper function
Posted by Nitin Rawat 8 months, 1 week ago 

On 3/19/2025 1:20 AM, Bjorn Andersson wrote:
> On Tue, Mar 18, 2025 at 08:19:44PM +0530, Nitin Rawat wrote:
>> Introduce ufs_qcom_phy_power_on and ufs_qcom_phy_power_off wrapper
>> functions with mutex protection to ensure safe usage of is_phy_pwr_on
>> and prevent possible race conditions.
>>
> 
> Please describe the problem properly here. Are you introducing the mutex
> because there is a problem, or because you want to be "safe"?
> 
> Why is it "refcounted", is the calling code paths no longer in sync? How
> long has the current implementation been broken?
> 
> Regards,
> Bjorn
> 

Hi Bjorn,

Thanks for the review. There are scenarios where ufshcd_link_startup() 
can call ufshcd_vops_link_startup_notify() multiple times during 
retries. This leads to the PHY reference count increasing continuously, 
preventing proper re-initialization of the PHY.

Recently, this issue was addressed with patch 7bac65687510 ("scsi: ufs: 
qcom: Power off the PHY if it was already powered on in 
ufs_qcom_power_up_sequence()"). However, I still want to maintain a 
reference count (ref_cnt) to safeguard against similar conditions in the 
code. Additionally, this approach helps avoid unnecessary phy_power_on 
and phy_power_off calls. Please let me know your thoughts.

Regrads,
Nitin




>> Co-developed-by: Can Guo <quic_cang@quicinc.com>
>> Signed-off-by: Can Guo <quic_cang@quicinc.com>
>> Signed-off-by: Nitin Rawat <quic_nitirawa@quicinc.com>
>> ---
>>   drivers/ufs/host/ufs-qcom.c | 44 +++++++++++++++++++++++++++++++------
>>   drivers/ufs/host/ufs-qcom.h |  4 ++++
>>   2 files changed, 41 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
>> index 5c7b6c75d669..8f80724e64b9 100644
>> --- a/drivers/ufs/host/ufs-qcom.c
>> +++ b/drivers/ufs/host/ufs-qcom.c
>> @@ -421,6 +421,38 @@ static u32 ufs_qcom_get_hs_gear(struct ufs_hba *hba)
>>   	return UFS_HS_G3;
>>   }
>>
>> +static int ufs_qcom_phy_power_on(struct ufs_hba *hba)
>> +{
>> +	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>> +	struct phy *phy = host->generic_phy;
>> +	int ret = 0;
>> +
>> +	guard(mutex)(&host->phy_mutex);
>> +	if (!host->is_phy_pwr_on) {
>> +		ret = phy_power_on(phy);
>> +		if (!ret)
>> +			host->is_phy_pwr_on = true;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static int ufs_qcom_phy_power_off(struct ufs_hba *hba)
>> +{
>> +	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>> +	struct phy *phy = host->generic_phy;
>> +	int ret = 0;
>> +
>> +	guard(mutex)(&host->phy_mutex);
>> +	if (host->is_phy_pwr_on) {
>> +		ret = phy_power_off(phy);
>> +		if (!ret)
>> +			host->is_phy_pwr_on = false;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>>   static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
>>   {
>>   	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>> @@ -449,7 +481,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
>>   		return ret;
>>
>>   	if (phy->power_count) {
>> -		phy_power_off(phy);
>> +		ufs_qcom_phy_power_off(hba);
>>   		phy_exit(phy);
>>   	}
>>
>> @@ -466,7 +498,7 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
>>   		goto out_disable_phy;
>>
>>   	/* power on phy - start serdes and phy's power and clocks */
>> -	ret = phy_power_on(phy);
>> +	ret = ufs_qcom_phy_power_on(hba);
>>   	if (ret) {
>>   		dev_err(hba->dev, "%s: phy power on failed, ret = %d\n",
>>   			__func__, ret);
>> @@ -1017,7 +1049,6 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>>   				 enum ufs_notify_change_status status)
>>   {
>>   	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>> -	struct phy *phy = host->generic_phy;
>>   	int err;
>>
>>   	/*
>> @@ -1037,7 +1068,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>>   				/* disable device ref_clk */
>>   				ufs_qcom_dev_ref_clk_ctrl(host, false);
>>   			}
>> -			err = phy_power_off(phy);
>> +			err = ufs_qcom_phy_power_off(hba);
>>   			if (err) {
>>   				dev_err(hba->dev, "phy power off failed, ret=%d\n", err);
>>   					return err;
>> @@ -1046,7 +1077,7 @@ static int ufs_qcom_setup_clocks(struct ufs_hba *hba, bool on,
>>   		break;
>>   	case POST_CHANGE:
>>   		if (on) {
>> -			err = phy_power_on(phy);
>> +			err = ufs_qcom_phy_power_on(hba);
>>   			if (err) {
>>   				dev_err(hba->dev, "phy power on failed, ret = %d\n", err);
>>   				return err;
>> @@ -1233,10 +1264,9 @@ static int ufs_qcom_init(struct ufs_hba *hba)
>>   static void ufs_qcom_exit(struct ufs_hba *hba)
>>   {
>>   	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>> -	struct phy *phy = host->generic_phy;
>>
>>   	ufs_qcom_disable_lane_clks(host);
>> -	phy_power_off(phy);
>> +	ufs_qcom_phy_power_off(hba);
>>   	phy_exit(host->generic_phy);
>>   }
>>
>> diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
>> index d0e6ec9128e7..3db29fbcd40b 100644
>> --- a/drivers/ufs/host/ufs-qcom.h
>> +++ b/drivers/ufs/host/ufs-qcom.h
>> @@ -252,6 +252,10 @@ struct ufs_qcom_host {
>>   	u32 phy_gear;
>>
>>   	bool esi_enabled;
>> +	/* flag to check if phy is powered on */
>> +	bool is_phy_pwr_on;
>> +	/* Protect the usage of is_phy_pwr_on against racing */
>> +	struct mutex phy_mutex;
>>   };
>>
>>   struct ufs_qcom_drvdata {
>> --
>> 2.48.1
>>
>>
Re: [PATCH V2 6/6] scsi: ufs: host : Introduce phy_power_on/off wrapper function
Posted by Bart Van Assche 9 months ago 
On 3/18/25 7:49 AM, Nitin Rawat wrote:

Just like the other patches in this series, the subject of this patch
should have the prefix "scsi: ufs: qcom:" instead of "scsi: ufs: host:"

> diff --git a/drivers/ufs/host/ufs-qcom.h b/drivers/ufs/host/ufs-qcom.h
> index d0e6ec9128e7..3db29fbcd40b 100644
> --- a/drivers/ufs/host/ufs-qcom.h
> +++ b/drivers/ufs/host/ufs-qcom.h
> @@ -252,6 +252,10 @@ struct ufs_qcom_host {
>   	u32 phy_gear;
> 
>   	bool esi_enabled;
> +	/* flag to check if phy is powered on */
> +	bool is_phy_pwr_on;
> +	/* Protect the usage of is_phy_pwr_on against racing */
> +	struct mutex phy_mutex;
>   };

Please reorder the above two structure members. Synchronization objects
should occur before the data members protected by these synchronization
objects in structure definitions.

It seems to me that phy_mutex not only serializes is_phy_pwr_on accesses
but that it also serializes phy_power_on() / phy_power_off() calls. If
this is the case, please mention this.

Thanks,

Bart.

Patchew 2.1-devel-b67e4c2

© 2016 - 2025 Red Hat, Inc.