[PATCH v2 1/2] regulator: pcf50633: Don't write to reserved bits of AUTO output voltage select register

[PATCH v2 1/2] regulator: pcf50633: Don't write to reserved bits of AUTO output voltage select register

[Axel Lin]

The datasheet says 00000000 to 00101110 are reserved, and the min value of the
voltage setting is 1.8 V.
Thus don't write 0 to AUTO output voltage select register (address 1Ah).

Table 50. AUTOOUT - AUTO output voltage select register (address 1Ah) bit description[1]
Bit Symbol Access Description
7:0 auto_out R/W VO(prog) = 0.625 + auto_out × 0.025 V
eg. 00000000 to 00101110: reserved
00101111: 1.8 V (min)
01010011: 2.7 V
01101010: 3.275 V
01101011: 3.300 V
01101100: 3.325 V
01111111 : 3.800 V (max)
..... .....
11111110 : 3.800 V
11111111 : 3.800 V

This patch also fixes a bug in pcf50633_regulator_list_voltage.
It is wrong to do "index += 0x2f" for PCF50633_REGULATOR_AUTO in
pcf50633_regulator_list_voltage. The purpose of adding 0x2f to index is because
current code return 0 in auto_voltage_bits when millivolts < 1800.
For millivolts > 1800, adding 0x2f to index is wrong.

We should handle this by
return 0 if the selector is in the reserved range of AUTOOUT.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
---
 drivers/regulator/pcf50633-regulator.c |   23 +++++------------------
 1 files changed, 5 insertions(+), 18 deletions(-)

diff --git a/drivers/regulator/pcf50633-regulator.c b/drivers/regulator/pcf50633-regulator.c
index 6db46c6..9ef7dff 100644
--- a/drivers/regulator/pcf50633-regulator.c
+++ b/drivers/regulator/pcf50633-regulator.c
@@ -52,7 +52,7 @@ static const u8 pcf50633_regulator_registers[PCF50633_NUM_REGULATORS] = {
 static u8 auto_voltage_bits(unsigned int millivolts)
 {
 	if (millivolts < 1800)
-		return 0;
+		return 0x2f;
 	if (millivolts > 3800)
 		return 0xff;
 
@@ -87,9 +87,6 @@ static u8 ldo_voltage_bits(unsigned int millivolts)
 /* Obtain voltage value from bits */
 static unsigned int auto_voltage_value(u8 bits)
 {
-	if (bits < 0x2f)
-		return 0;
-
 	return 625 + (bits * 25);
 }
 
@@ -161,6 +158,9 @@ static int pcf50633_regulator_voltage_value(enum pcf50633_regulator_id id,
 
 	switch (id) {
 	case PCF50633_REGULATOR_AUTO:
+		/* AUTOOUT: 00000000 to 00101110 are reserved */
+		if (bits < 0x2f)
+			return 0;
 		millivolts = auto_voltage_value(bits);
 		break;
 	case PCF50633_REGULATOR_DOWN1:
@@ -208,20 +208,7 @@ static int pcf50633_regulator_get_voltage(struct regulator_dev *rdev)
 static int pcf50633_regulator_list_voltage(struct regulator_dev *rdev,
 						unsigned int index)
 {
-	struct pcf50633 *pcf;
-	int regulator_id;
-
-	pcf = rdev_get_drvdata(rdev);
-
-	regulator_id = rdev_get_id(rdev);
-
-	switch (regulator_id) {
-	case PCF50633_REGULATOR_AUTO:
-		index += 0x2f;
-		break;
-	default:
-		break;
-	}
+	int regulator_id = rdev_get_id(rdev);
 
 	return pcf50633_regulator_voltage_value(regulator_id, index);
 }
-- 
1.7.5.4

[PATCH v2 2/2] regulator: Convert pcf50633 to get_voltage_sel

[Axel Lin]

Convert pcf50633 to get_voltage_sel and then we can remove
pcf50633_regulator_voltage_value function and move its implementation
to pcf50633_regulator_list_voltage.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
---
 drivers/regulator/pcf50633-regulator.c |   65 ++++++++++++++-----------------
 1 files changed, 29 insertions(+), 36 deletions(-)

diff --git a/drivers/regulator/pcf50633-regulator.c b/drivers/regulator/pcf50633-regulator.c
index 9ef7dff..b02cbb9 100644
--- a/drivers/regulator/pcf50633-regulator.c
+++ b/drivers/regulator/pcf50633-regulator.c
@@ -151,23 +151,43 @@ static int pcf50633_regulator_set_voltage(struct regulator_dev *rdev,
 	return pcf50633_reg_write(pcf, regnr, volt_bits);
 }
 
-static int pcf50633_regulator_voltage_value(enum pcf50633_regulator_id id,
-						u8 bits)
+static int pcf50633_regulator_get_voltage_sel(struct regulator_dev *rdev)
 {
+	struct pcf50633 *pcf;
+	int regulator_id;
+	u8 volt_bits, regnr;
+
+	pcf = rdev_get_drvdata(rdev);
+
+	regulator_id = rdev_get_id(rdev);
+	if (regulator_id >= PCF50633_NUM_REGULATORS)
+		return -EINVAL;
+
+	regnr = pcf50633_regulator_registers[regulator_id];
+
+	volt_bits = pcf50633_reg_read(pcf, regnr);
+
+	return volt_bits;
+}
+
+static int pcf50633_regulator_list_voltage(struct regulator_dev *rdev,
+						unsigned int index)
+{
+	int regulator_id = rdev_get_id(rdev);
 	int millivolts;
 
-	switch (id) {
+	switch (regulator_id) {
 	case PCF50633_REGULATOR_AUTO:
 		/* AUTOOUT: 00000000 to 00101110 are reserved */
-		if (bits < 0x2f)
+		if (index < 0x2f)
 			return 0;
-		millivolts = auto_voltage_value(bits);
+		millivolts = auto_voltage_value(index);
 		break;
 	case PCF50633_REGULATOR_DOWN1:
-		millivolts = down_voltage_value(bits);
+		millivolts = down_voltage_value(index);
 		break;
 	case PCF50633_REGULATOR_DOWN2:
-		millivolts = down_voltage_value(bits);
+		millivolts = down_voltage_value(index);
 		break;
 	case PCF50633_REGULATOR_LDO1:
 	case PCF50633_REGULATOR_LDO2:
@@ -177,7 +197,7 @@ static int pcf50633_regulator_voltage_value(enum pcf50633_regulator_id id,
 	case PCF50633_REGULATOR_LDO6:
 	case PCF50633_REGULATOR_HCLDO:
 	case PCF50633_REGULATOR_MEMLDO:
-		millivolts = ldo_voltage_value(bits);
+		millivolts = ldo_voltage_value(index);
 		break;
 	default:
 		return -EINVAL;
@@ -186,33 +206,6 @@ static int pcf50633_regulator_voltage_value(enum pcf50633_regulator_id id,
 	return millivolts * 1000;
 }
 
-static int pcf50633_regulator_get_voltage(struct regulator_dev *rdev)
-{
-	struct pcf50633 *pcf;
-	int regulator_id;
-	u8 volt_bits, regnr;
-
-	pcf = rdev_get_drvdata(rdev);
-
-	regulator_id = rdev_get_id(rdev);
-	if (regulator_id >= PCF50633_NUM_REGULATORS)
-		return -EINVAL;
-
-	regnr = pcf50633_regulator_registers[regulator_id];
-
-	volt_bits = pcf50633_reg_read(pcf, regnr);
-
-	return pcf50633_regulator_voltage_value(regulator_id, volt_bits);
-}
-
-static int pcf50633_regulator_list_voltage(struct regulator_dev *rdev,
-						unsigned int index)
-{
-	int regulator_id = rdev_get_id(rdev);
-
-	return pcf50633_regulator_voltage_value(regulator_id, index);
-}
-
 static int pcf50633_regulator_enable(struct regulator_dev *rdev)
 {
 	struct pcf50633 *pcf = rdev_get_drvdata(rdev);
@@ -265,7 +258,7 @@ static int pcf50633_regulator_is_enabled(struct regulator_dev *rdev)
 
 static struct regulator_ops pcf50633_regulator_ops = {
 	.set_voltage = pcf50633_regulator_set_voltage,
-	.get_voltage = pcf50633_regulator_get_voltage,
+	.get_voltage_sel = pcf50633_regulator_get_voltage_sel,
 	.list_voltage = pcf50633_regulator_list_voltage,
 	.enable = pcf50633_regulator_enable,
 	.disable = pcf50633_regulator_disable,
-- 
1.7.5.4

Re: [PATCH v2 2/2] regulator: Convert pcf50633 to get_voltage_sel

[Lars-Peter Clausen]

On 03/17/2012 01:08 AM, Axel Lin wrote:
> Convert pcf50633 to get_voltage_sel and then we can remove
> pcf50633_regulator_voltage_value function and move its implementation
> to pcf50633_regulator_list_voltage.
> 
> Signed-off-by: Axel Lin <axel.lin@gmail.com>

Acked-by: Lars-Peter Clausen <lars@metafoo.de>

One minor comment inline though.

> ---
>  drivers/regulator/pcf50633-regulator.c |   65 ++++++++++++++-----------------
>  1 files changed, 29 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/regulator/pcf50633-regulator.c b/drivers/regulator/pcf50633-regulator.c
> index 9ef7dff..b02cbb9 100644
> --- a/drivers/regulator/pcf50633-regulator.c
> +++ b/drivers/regulator/pcf50633-regulator.c
> @@ -151,23 +151,43 @@ static int pcf50633_regulator_set_voltage(struct regulator_dev *rdev,
>  	return pcf50633_reg_write(pcf, regnr, volt_bits);
>  }
>  
> -static int pcf50633_regulator_voltage_value(enum pcf50633_regulator_id id,
> -						u8 bits)
> +static int pcf50633_regulator_get_voltage_sel(struct regulator_dev *rdev)
>  {
> +	struct pcf50633 *pcf;
> +	int regulator_id;
> +	u8 volt_bits, regnr;
> +
> +	pcf = rdev_get_drvdata(rdev);
> +
> +	regulator_id = rdev_get_id(rdev);
> +	if (regulator_id >= PCF50633_NUM_REGULATORS)
> +		return -EINVAL;
> +
> +	regnr = pcf50633_regulator_registers[regulator_id];
> +
> +	volt_bits = pcf50633_reg_read(pcf, regnr);
> +
> +	return volt_bits;

Might as well just do "return pcf50633_reg_read(pcf, regnr);"

Re: [PATCH v2 1/2] regulator: pcf50633: Don't write to reserved bits of AUTO output voltage select register

[Lars-Peter Clausen]

On 03/17/2012 01:07 AM, Axel Lin wrote:
> The datasheet says 00000000 to 00101110 are reserved, and the min value of the
> voltage setting is 1.8 V.
> Thus don't write 0 to AUTO output voltage select register (address 1Ah).
> 
> Table 50. AUTOOUT - AUTO output voltage select register (address 1Ah) bit description[1]
> Bit Symbol Access Description
> 7:0 auto_out R/W VO(prog) = 0.625 + auto_out × 0.025 V
> eg. 00000000 to 00101110: reserved
> 00101111: 1.8 V (min)
> 01010011: 2.7 V
> 01101010: 3.275 V
> 01101011: 3.300 V
> 01101100: 3.325 V
> 01111111 : 3.800 V (max)
> ..... .....
> 11111110 : 3.800 V
> 11111111 : 3.800 V
> 
> This patch also fixes a bug in pcf50633_regulator_list_voltage.
> It is wrong to do "index += 0x2f" for PCF50633_REGULATOR_AUTO in
> pcf50633_regulator_list_voltage. The purpose of adding 0x2f to index is because
> current code return 0 in auto_voltage_bits when millivolts < 1800.
> For millivolts > 1800, adding 0x2f to index is wrong.
> 

I think you misunderstood what the current code does. The first usable voltage
is 1.8V which is equal to a index of of 0x2f. So the driver adds 0x2f to the
index so that there is not a headroom of 0x2f unusable voltages. So a selector
of 0 translates to 1.8V, a selector of 1 translates to 1.825V and so on.

I can see why you'd want to change it to simplify the code, but you also have
to change the number of voltages for the AUTO regulator to 128.

Re: [PATCH v2 1/2] regulator: pcf50633: Don't write to reserved bits of AUTO output voltage select register

[Axel Lin]

2012/3/18 Lars-Peter Clausen <lars@metafoo.de>:
> On 03/17/2012 01:07 AM, Axel Lin wrote:
>> The datasheet says 00000000 to 00101110 are reserved, and the min value of the
>> voltage setting is 1.8 V.
>> Thus don't write 0 to AUTO output voltage select register (address 1Ah).
>>
>> Table 50. AUTOOUT - AUTO output voltage select register (address 1Ah) bit description[1]
>> Bit Symbol Access Description
>> 7:0 auto_out R/W VO(prog) = 0.625 + auto_out × 0.025 V
>> eg. 00000000 to 00101110: reserved
>> 00101111: 1.8 V (min)
>> 01010011: 2.7 V
>> 01101010: 3.275 V
>> 01101011: 3.300 V
>> 01101100: 3.325 V
>> 01111111 : 3.800 V (max)
>> ..... .....
>> 11111110 : 3.800 V
>> 11111111 : 3.800 V
>>
>> This patch also fixes a bug in pcf50633_regulator_list_voltage.
>> It is wrong to do "index += 0x2f" for PCF50633_REGULATOR_AUTO in
>> pcf50633_regulator_list_voltage. The purpose of adding 0x2f to index is because
>> current code return 0 in auto_voltage_bits when millivolts < 1800.
>> For millivolts > 1800, adding 0x2f to index is wrong.
>>
>
> I think you misunderstood what the current code does. The first usable voltage
> is 1.8V which is equal to a index of of 0x2f. So the driver adds 0x2f to the
> index so that there is not a headroom of 0x2f unusable voltages. So a selector
> of 0 translates to 1.8V, a selector of 1 translates to 1.825V and so on.
I think what I wry to explain is:
In regulator core _regulator_do_set_voltage function:

        if (rdev->desc->ops->set_voltage) {
                ret = rdev->desc->ops->set_voltage(rdev, min_uV, max_uV,
                                                   &selector);

                if (rdev->desc->ops->list_voltage)
                        selector = rdev->desc->ops->list_voltage(rdev,
                                                                 selector);
                else
                        selector = -1;

The list_voltage call here takes the selector got from set_voltage callback.
Thus adding 0x2f to the index in pcf50633_regulator_list_voltage looks
wrong to me.

e.g.
If min_uV < 1.8V, pcf50633_regulator_set_voltage sets 0 to selector.
For this case, adding 0x2f to the index in
pcf50633_regulator_list_voltage is exactly what you want.
However, if min_uV == 1.8V, pcf50633_regulator_set_voltage sets 0x2f
to selector.
Adding 0x2f to the index in pcf50633_regulator_list_voltage in this
case is wrong.

What this patch does is:
The minimal voltage setting for AUTOOUT is 0x2f.
Thus for the case min_uV < 1.8, set the voltage setting to 1.8V by writting
0x2f to AUTOOUT register and set selector = 0x2f.
So we don't write the rserved range to AUTOOUT register.
Which means the possible range of AUTOOUT register value is 0x2f ~ 0xff.

We have no problem in regulator_get_voltage.
Since we won't write 0~0x2e to AUTOOUT register, we have no problem converting
the bits we read to voltage. The equation in auto_voltage_value works fine.

For list_voltage, we need to take into account the case selector is 0 ~ 0x2e
because the regulator core assumes the selector is starting from 0.
This patch returns 0 for the cases selector is 0 ~ 0x2e, which means
"this selector code can't be used on this system".

>
> I can see why you'd want to change it to simplify the code, but you also have
> to change the number of voltages for the AUTO regulator to 128.
yes, I missed that.
The regulator core iterates from 0 to n_voltages to find the small voltage
in the specific range.
So yes, I think the n_voltages settings for AUTOOUT should be 128 now,
including the reserved range of AUTOOUT.

I'll send a V3 for review and update the commit log.
Thanks,
Axel

Re: [PATCH v2 1/2] regulator: pcf50633: Don't write to reserved bits of AUTO output voltage select register

[Lars-Peter Clausen]

On 03/19/2012 03:53 AM, Axel Lin wrote:
> 2012/3/18 Lars-Peter Clausen <lars@metafoo.de>:
>> On 03/17/2012 01:07 AM, Axel Lin wrote:
>>> The datasheet says 00000000 to 00101110 are reserved, and the min value of the
>>> voltage setting is 1.8 V.
>>> Thus don't write 0 to AUTO output voltage select register (address 1Ah).
>>>
>>> Table 50. AUTOOUT - AUTO output voltage select register (address 1Ah) bit description[1]
>>> Bit Symbol Access Description
>>> 7:0 auto_out R/W VO(prog) = 0.625 + auto_out × 0.025 V
>>> eg. 00000000 to 00101110: reserved
>>> 00101111: 1.8 V (min)
>>> 01010011: 2.7 V
>>> 01101010: 3.275 V
>>> 01101011: 3.300 V
>>> 01101100: 3.325 V
>>> 01111111 : 3.800 V (max)
>>> ..... .....
>>> 11111110 : 3.800 V
>>> 11111111 : 3.800 V
>>>
>>> This patch also fixes a bug in pcf50633_regulator_list_voltage.
>>> It is wrong to do "index += 0x2f" for PCF50633_REGULATOR_AUTO in
>>> pcf50633_regulator_list_voltage. The purpose of adding 0x2f to index is because
>>> current code return 0 in auto_voltage_bits when millivolts < 1800.
>>> For millivolts > 1800, adding 0x2f to index is wrong.
>>>
>>
>> I think you misunderstood what the current code does. The first usable voltage
>> is 1.8V which is equal to a index of of 0x2f. So the driver adds 0x2f to the
>> index so that there is not a headroom of 0x2f unusable voltages. So a selector
>> of 0 translates to 1.8V, a selector of 1 translates to 1.825V and so on.
> I think what I wry to explain is:
> In regulator core _regulator_do_set_voltage function:
> 
>         if (rdev->desc->ops->set_voltage) {
>                 ret = rdev->desc->ops->set_voltage(rdev, min_uV, max_uV,
>                                                    &selector);
> 
>                 if (rdev->desc->ops->list_voltage)
>                         selector = rdev->desc->ops->list_voltage(rdev,
>                                                                  selector);
>                 else
>                         selector = -1;
> 
> The list_voltage call here takes the selector got from set_voltage callback.
> Thus adding 0x2f to the index in pcf50633_regulator_list_voltage looks
> wrong to me.
> 

Ah ok, now I understand what you mean. When the selector parameter to
set_voltage was introduced we already had list_voltage adding the 0x2f, so
from my point of view list_voltage is correct and the bug is in the commit
which introduced the selector parameter to select voltage, that's why I was
confused as to why you think there was a bug in list_voltage. But it all
makes sense now, thanks.

Luckily the bug is not so critical, since selector is not really used in
_regulator_do_set_voltage in this case except for the trace message.

- Lars