[PATCH v4 0/5] scsi: ufs: Fix regulator operations and remove "<name>-fixed-regulator" device tree property

[PATCH v4 0/5] scsi: ufs: Fix regulator operations and remove "<name>-fixed-regulator" device tree property

[Stanley Chu]

Upload v4 to fix little commit messages and invite more platform reviewers.

This patch series fixes UFS regulator operations, including voltage and current (re-)configuration flow during UFS initialization and power modes switching.

In the end, remove "<name>-fixed-regulator" device tree property because it is not necessary anymore after fixes.

V4:
- Fix commit messages (Avri Altman).
- Fix tags (Alim Akhtar).
- Invite more reviewers.

V3:
- Fix and add more details in commit messages.
- Add one patch "scsi: ufs: Avoid configuring undefined voltage range on a regulator".

V2:
- Add two patches to prepare to and remove "<name>-fixed-regulator" device tree property.
- Add more details on patch "scsi: ufs: remove unused min_uA field in struct ufs_vreg" (Marc Gonzalez).

Stanley Chu (5):
  scsi: ufs: Remove unused min_uA field in struct ufs_vreg
  scsi: ufs: Avoid configuring regulator with undefined voltage range
  scsi: ufs: Fix regulator load and icc-level configuration
  scsi: ufs: Change "<name>-max-microamp" to non-mandatory property
  scsi: ufs: Remove "<name>-fixed-regulator" device tree property

 drivers/scsi/ufs/ufs.h           |  1 -
 drivers/scsi/ufs/ufshcd-pltfrm.c | 14 +++-----------
 drivers/scsi/ufs/ufshcd.c        | 28 ++++++++++++++++++++--------
 3 files changed, 23 insertions(+), 20 deletions(-)

-- 
2.18.0


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[PATCH v4 1/5] scsi: ufs: Remove unused min_uA field in struct ufs_vreg

[Stanley Chu]

There are two fields related to regulator current limit in struct
ufs_vreg: "min_uA" and "max_uA".

"max_uA" is probed by "<name>-max-microamp" property from device
tree and used for

- regulator_set_load operations, and
- icc_level configuration in device.

However "min_uA" field is not used anywhere, thus we can remove it.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Marc Gonzalez <marc.w.gonzalez@free.fr>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Acked-by: Alim Akhtar <alim.akhtar@samsung.com>
---
 drivers/scsi/ufs/ufs.h           | 1 -
 drivers/scsi/ufs/ufshcd-pltfrm.c | 1 -
 2 files changed, 2 deletions(-)

diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
index 21e4ccb5ba6e..99a9c4d16f6b 100644
--- a/drivers/scsi/ufs/ufs.h
+++ b/drivers/scsi/ufs/ufs.h
@@ -516,7 +516,6 @@ struct ufs_vreg {
 	bool enabled;
 	int min_uV;
 	int max_uV;
-	int min_uA;
 	int max_uA;
 };
 
diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c b/drivers/scsi/ufs/ufshcd-pltfrm.c
index 27213676329c..32cf8c56f029 100644
--- a/drivers/scsi/ufs/ufshcd-pltfrm.c
+++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
@@ -164,7 +164,6 @@ static int ufshcd_populate_vreg(struct device *dev, const char *name,
 		goto out;
 	}
 
-	vreg->min_uA = 0;
 	if (!strcmp(name, "vcc")) {
 		if (of_property_read_bool(np, "vcc-supply-1p8")) {
 			vreg->min_uV = UFS_VREG_VCC_1P8_MIN_UV;
-- 
2.18.0


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[PATCH v4 2/5] scsi: ufs: Avoid configuring regulator with undefined voltage range

[Stanley Chu]

For regulators used by UFS, vcc, vccq and vccq2 will have voltage range
initialized by ufshcd_populate_vreg(), however other regulators may
have undefined voltage range if dt-bindings have no such definition.

In above undefined case, both "min_uV" and "max_uV" fields in ufs_vreg
struct will be zero values and these values will be configured on
regulators in different power modes.

Currently this may have no harm if both "min_uV" and "max_uV"
always keep "zero values" because regulator_set_voltage() will always
bypass such invalid values and return "good" results.

However improper values shall be fixed to avoid potential bugs.
Simply bypass voltage configuration if voltage range is not defined.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Acked-by: Alim Akhtar <alim.akhtar@samsung.com>
---
 drivers/scsi/ufs/ufshcd.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index e040f9dd9ff3..81d99aebb867 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -7039,12 +7039,15 @@ static int ufshcd_config_vreg(struct device *dev,
 	name = vreg->name;
 
 	if (regulator_count_voltages(reg) > 0) {
-		min_uV = on ? vreg->min_uV : 0;
-		ret = regulator_set_voltage(reg, min_uV, vreg->max_uV);
-		if (ret) {
-			dev_err(dev, "%s: %s set voltage failed, err=%d\n",
+		if (vreg->min_uV && vreg->max_uV) {
+			min_uV = on ? vreg->min_uV : 0;
+			ret = regulator_set_voltage(reg, min_uV, vreg->max_uV);
+			if (ret) {
+				dev_err(dev,
+					"%s: %s set voltage failed, err=%d\n",
 					__func__, name, ret);
-			goto out;
+				goto out;
+			}
 		}
 
 		uA_load = on ? vreg->max_uA : 0;
-- 
2.18.0


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[PATCH v4 3/5] scsi: ufs: Fix regulator load and icc-level configuration

[Stanley Chu]

Currently if a regulator has "<name>-fixed-regulator"
property in device tree, it will skip current limit initialization.
This lead to a zero "max_uA" value in struct ufs_vreg.

However, "regulator_set_load" operation shall be required
on regulators which have valid current limits, otherwise a zero
"max_uA" set by "regulator_set_load" may cause unexpected behavior
when this regulator is enabled or set as high power mode.

Similarly, in device's icc_level configuration flow, the target
icc_level shall be updated if regulator also has valid current limit,
otherwise a wrong icc_level will be calculated by zero "max_uA" and
thus causes unexpected results after it is written to device.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Acked-by: Alim Akhtar <alim.akhtar@samsung.com>
---
 drivers/scsi/ufs/ufshcd.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 81d99aebb867..5ba49c8cd2a3 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6294,19 +6294,19 @@ static u32 ufshcd_find_max_sup_active_icc_level(struct ufs_hba *hba,
 		goto out;
 	}
 
-	if (hba->vreg_info.vcc)
+	if (hba->vreg_info.vcc && hba->vreg_info.vcc->max_uA)
 		icc_level = ufshcd_get_max_icc_level(
 				hba->vreg_info.vcc->max_uA,
 				POWER_DESC_MAX_ACTV_ICC_LVLS - 1,
 				&desc_buf[PWR_DESC_ACTIVE_LVLS_VCC_0]);
 
-	if (hba->vreg_info.vccq)
+	if (hba->vreg_info.vccq && hba->vreg_info.vccq->max_uA)
 		icc_level = ufshcd_get_max_icc_level(
 				hba->vreg_info.vccq->max_uA,
 				icc_level,
 				&desc_buf[PWR_DESC_ACTIVE_LVLS_VCCQ_0]);
 
-	if (hba->vreg_info.vccq2)
+	if (hba->vreg_info.vccq2 && hba->vreg_info.vccq2->max_uA)
 		icc_level = ufshcd_get_max_icc_level(
 				hba->vreg_info.vccq2->max_uA,
 				icc_level,
@@ -7004,6 +7004,15 @@ static int ufshcd_config_vreg_load(struct device *dev, struct ufs_vreg *vreg,
 	if (!vreg)
 		return 0;
 
+	/*
+	 * "set_load" operation shall be required on those regulators
+	 * which specifically configured current limitation. Otherwise
+	 * zero max_uA may cause unexpected behavior when regulator is
+	 * enabled or set as high power mode.
+	 */
+	if (!vreg->max_uA)
+		return 0;
+
 	ret = regulator_set_load(vreg->reg, ua);
 	if (ret < 0) {
 		dev_err(dev, "%s: %s set load (ua=%d) failed, err=%d\n",
-- 
2.18.0


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[PATCH v4 4/5] scsi: ufs: Change "<name>-max-microamp" to non-mandatory property

[Stanley Chu]

In dt-bindings for ufs, "<name>-max-microamp" property indicates
current limit and is mandatory if "<name>-fixed-regulator" is not
defined on a specified regulator.

However, in some platforms, regulators without "<name>-fixed-regulator"
property may not need to define their current limit because they may
want to define voltage range only for proper voltage switching in
different power modes, especially for vcc, vccq or vccq2.

Currently missing "<name>-max-microamp" property in device tree will
lead initialization to fail, thus such limitation shall be
resolved to tolerate this kind of regulators.

After resolving this, regulators without "<name>-max-microamp"
property will have undefined "max current" value, i.e., zero value
in "max_uA" field in struct ufs_vreg. Because we do bypass current
switching operation (by regulator_set_load) in case of undefined
current limit, this patch shall be safe.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Acked-by: Alim Akhtar <alim.akhtar@samsung.com>
---
 drivers/scsi/ufs/ufshcd-pltfrm.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c b/drivers/scsi/ufs/ufshcd-pltfrm.c
index 32cf8c56f029..2420e6962219 100644
--- a/drivers/scsi/ufs/ufshcd-pltfrm.c
+++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
@@ -157,11 +157,9 @@ static int ufshcd_populate_vreg(struct device *dev, const char *name,
 		goto out;
 
 	snprintf(prop_name, MAX_PROP_SIZE, "%s-max-microamp", name);
-	ret = of_property_read_u32(np, prop_name, &vreg->max_uA);
-	if (ret) {
-		dev_err(dev, "%s: unable to find %s err %d\n",
-				__func__, prop_name, ret);
-		goto out;
+	if (of_property_read_u32(np, prop_name, &vreg->max_uA)) {
+		dev_info(dev, "%s: unable to find %s\n", __func__, prop_name);
+		vreg->max_uA = 0;
 	}
 
 	if (!strcmp(name, "vcc")) {
-- 
2.18.0


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[PATCH v4 5/5] scsi: ufs: Remove "<name>-fixed-regulator" device tree property

[Stanley Chu]

"<name>-fixed-regulator" device tree property can be
safely removed because below things are fixed or resolved,

1. "<name>-max-microamp" becomes optional property: Undefined
   "<name>-max-microamp" will not cause initialization fail if
   "<name>-fixed-regulator" is not defined.

2. Current switching operation (by regulator_set_load) now has rules:
   Regulators will have undefined current limit if
   "<name>-fixed-regulator" is not defined. But this is safe because
   only regulator which has configured current limit from
   "<name>-max-microamp" property is allowed to change its load.

Although "<name>-fixed-regulator" is not used in any dt-bindings
in tree, this patch is still safe for regulators already defined
"<name>-fixed-regulator". To be more clear, if a regulator defined
"<name>-fixed-regulator" before, the behavior difference after
this patch is,

1. "<name>-max-microamp":
   If a regulator defined "<name>-fixed-regulator", it is not necessary
   to define "<name>-max-microamp" property in device tree and it is
   expected to have an undefined current limit, i.e., "max_uA" field
   is zero in struct ufs_vreg. This is exactly the same as patched.

2. "vcc-supply-1p8" or volatge range settings:
   * For vcc, vccq or vccq2, these three regulators shall not define
     "<name>-fixed-regulator" because defining it will lead to
     undefined voltage range and thus voltage switching will be
     unexpected.
   * For other regulators with undefined voltage range, voltage range
     will be still undefined after patched.

Therefore this patch is safe for all existed regulators with
"<name>-fixed-regulator" property already defined.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Acked-by: Alim Akhtar <alim.akhtar@samsung.com>
---
 drivers/scsi/ufs/ufshcd-pltfrm.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c b/drivers/scsi/ufs/ufshcd-pltfrm.c
index 2420e6962219..7b404df965b2 100644
--- a/drivers/scsi/ufs/ufshcd-pltfrm.c
+++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
@@ -151,11 +151,6 @@ static int ufshcd_populate_vreg(struct device *dev, const char *name,
 
 	vreg->name = kstrdup(name, GFP_KERNEL);
 
-	/* if fixed regulator no need further initialization */
-	snprintf(prop_name, MAX_PROP_SIZE, "%s-fixed-regulator", name);
-	if (of_property_read_bool(np, prop_name))
-		goto out;
-
 	snprintf(prop_name, MAX_PROP_SIZE, "%s-max-microamp", name);
 	if (of_property_read_u32(np, prop_name, &vreg->max_uA)) {
 		dev_info(dev, "%s: unable to find %s\n", __func__, prop_name);
-- 
2.18.0


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Re: [PATCH v4 0/5] scsi: ufs: Fix regulator operations and remove "<name>-fixed-regulator" device tree property

[Martin K. Petersen]

Stanley,

> Upload v4 to fix little commit messages and invite more platform
> reviewers.
>
> This patch series fixes UFS regulator operations, including voltage
> and current (re-)configuration flow during UFS initialization and
> power modes switching.
>
> In the end, remove "<name>-fixed-regulator" device tree property
> because it is not necessary anymore after fixes.

Applied to 5.2/scsi-queue. Thank you!

-- 
Martin K. Petersen	Oracle Linux Engineering

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