[PATCH RFT] regulator: max8972: Fix setting ramp delay

[PATCH RFT] regulator: max8972: Fix setting ramp delay

[Axel Lin]

Current code can set ramp delay to a wrong setting that the return value
from .set_voltage_time_sel is not enough for proper delay.
Fix the logic in .set_ramp_delay and also remove unused ret_val variable.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
---
 drivers/regulator/max8973-regulator.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/regulator/max8973-regulator.c b/drivers/regulator/max8973-regulator.c
index 08d2f13..3958f50 100644
--- a/drivers/regulator/max8973-regulator.c
+++ b/drivers/regulator/max8973-regulator.c
@@ -271,22 +271,18 @@ static int max8973_set_ramp_delay(struct regulator_dev *rdev,
 	struct max8973_chip *max = rdev_get_drvdata(rdev);
 	unsigned int control;
 	int ret;
-	int ret_val;
 
 	/* Set ramp delay */
-	if (ramp_delay < 25000) {
+	if (ramp_delay <= 12000)
 		control = MAX8973_RAMP_12mV_PER_US;
-		ret_val = 12000;
-	} else if (ramp_delay < 50000) {
+	else if (ramp_delay <= 25000)
 		control = MAX8973_RAMP_25mV_PER_US;
-		ret_val = 25000;
-	} else if (ramp_delay < 200000) {
+	else if (ramp_delay <= 50000)
 		control = MAX8973_RAMP_50mV_PER_US;
-		ret_val = 50000;
-	} else {
+	else if (ramp_delay <= 200000)
 		control = MAX8973_RAMP_200mV_PER_US;
-		ret_val = 200000;
-	}
+	else
+		return -EINVAL;
 
 	ret = regmap_update_bits(max->regmap, MAX8973_CONTROL1,
 			MAX8973_RAMP_MASK, control);
-- 
2.5.0

Re: [PATCH RFT] regulator: max8972: Fix setting ramp delay

[Krzysztof Kozlowski]

On 05/29/2016 01:16 PM, Axel Lin wrote:
> Current code can set ramp delay to a wrong setting that the return value
> from .set_voltage_time_sel is not enough for proper delay.

I don't understand what yo wanted to say here. What wrong setting is
possible? Why do you mention set_voltage_time_sel() here?

Can you elaborate?

The only difference I spotted is how you round up the ramp_delay values.

Best regards,
Krzysztof

> Fix the logic in .set_ramp_delay and also remove unused ret_val variable.
> 
> Signed-off-by: Axel Lin <axel.lin@ingics.com>
> ---
>  drivers/regulator/max8973-regulator.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/regulator/max8973-regulator.c b/drivers/regulator/max8973-regulator.c
> index 08d2f13..3958f50 100644
> --- a/drivers/regulator/max8973-regulator.c
> +++ b/drivers/regulator/max8973-regulator.c
> @@ -271,22 +271,18 @@ static int max8973_set_ramp_delay(struct regulator_dev *rdev,
>  	struct max8973_chip *max = rdev_get_drvdata(rdev);
>  	unsigned int control;
>  	int ret;
> -	int ret_val;
>  
>  	/* Set ramp delay */
> -	if (ramp_delay < 25000) {
> +	if (ramp_delay <= 12000)
>  		control = MAX8973_RAMP_12mV_PER_US;
> -		ret_val = 12000;
> -	} else if (ramp_delay < 50000) {
> +	else if (ramp_delay <= 25000)
>  		control = MAX8973_RAMP_25mV_PER_US;
> -		ret_val = 25000;
> -	} else if (ramp_delay < 200000) {
> +	else if (ramp_delay <= 50000)
>  		control = MAX8973_RAMP_50mV_PER_US;
> -		ret_val = 50000;
> -	} else {
> +	else if (ramp_delay <= 200000)
>  		control = MAX8973_RAMP_200mV_PER_US;
> -		ret_val = 200000;
> -	}
> +	else
> +		return -EINVAL;
>  
>  	ret = regmap_update_bits(max->regmap, MAX8973_CONTROL1,
>  			MAX8973_RAMP_MASK, control);
> 

Re: [PATCH RFT] regulator: max8972: Fix setting ramp delay

[Axel Lin]

2016-05-30 16:48 GMT+08:00 Krzysztof Kozlowski <k.kozlowski@samsung.com>:
> On 05/29/2016 01:16 PM, Axel Lin wrote:
>> Current code can set ramp delay to a wrong setting that the return value
>> from .set_voltage_time_sel is not enough for proper delay.
>
> I don't understand what yo wanted to say here. What wrong setting is
> possible? Why do you mention set_voltage_time_sel() here?
>
> Can you elaborate?
>
> The only difference I spotted is how you round up the ramp_delay values.

Assume rdev->constraints->ramp_delay is 20000.

Original code will set MAX8973_RAMP_12mV_PER_US.

However, in regulator_set_voltage_time_sel()
        return DIV_ROUND_UP(abs(new_volt - old_volt), ramp_delay);

This return value is not enough if the device is using MAX8973_RAMP_12mV_PER_US
setting.

Re: [PATCH RFT] regulator: max8972: Fix setting ramp delay

[Krzysztof Kozlowski]

On 05/30/2016 10:52 AM, Axel Lin wrote:
> 2016-05-30 16:48 GMT+08:00 Krzysztof Kozlowski <k.kozlowski@samsung.com>:
>> On 05/29/2016 01:16 PM, Axel Lin wrote:
>>> Current code can set ramp delay to a wrong setting that the return value
>>> from .set_voltage_time_sel is not enough for proper delay.
>>
>> I don't understand what yo wanted to say here. What wrong setting is
>> possible? Why do you mention set_voltage_time_sel() here?
>>
>> Can you elaborate?
>>
>> The only difference I spotted is how you round up the ramp_delay values.
> 
> Assume rdev->constraints->ramp_delay is 20000.
> 
> Original code will set MAX8973_RAMP_12mV_PER_US.
> 
> However, in regulator_set_voltage_time_sel()
>         return DIV_ROUND_UP(abs(new_volt - old_volt), ramp_delay);
> 
> This return value is not enough if the device is using MAX8973_RAMP_12mV_PER_US
> setting.

Thanks, now it makes sense but the commit message needs improvements.
The problem is that current code for .set_ramp_delay() rounds down the
value written to register, while the implementation of
.set_voltage_time_sel() works on original constraints (not rounded down).

Please, fix the message.

Best regards,
Krzysztof

Applied "regulator: max8973: Fix setting ramp delay" to the regulator tree

[Mark Brown]

The patch

   regulator: max8973: Fix setting ramp delay

has been applied to the regulator tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From d0abd6f5f5eac758f4bcf4001f6cc377320ebc84 Mon Sep 17 00:00:00 2001
From: Axel Lin <axel.lin@ingics.com>
Date: Sun, 29 May 2016 19:20:03 +0800
Subject: [PATCH] regulator: max8973: Fix setting ramp delay

Current code can set ramp delay to a wrong setting that the return value
from .set_voltage_time_sel is not enough for proper delay.
Fix the logic in .set_ramp_delay and also remove unused ret_val variable.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/regulator/max8973-regulator.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/regulator/max8973-regulator.c b/drivers/regulator/max8973-regulator.c
index 08d2f13eca00..3958f50c5975 100644
--- a/drivers/regulator/max8973-regulator.c
+++ b/drivers/regulator/max8973-regulator.c
@@ -271,22 +271,18 @@ static int max8973_set_ramp_delay(struct regulator_dev *rdev,
 	struct max8973_chip *max = rdev_get_drvdata(rdev);
 	unsigned int control;
 	int ret;
-	int ret_val;
 
 	/* Set ramp delay */
-	if (ramp_delay < 25000) {
+	if (ramp_delay <= 12000)
 		control = MAX8973_RAMP_12mV_PER_US;
-		ret_val = 12000;
-	} else if (ramp_delay < 50000) {
+	else if (ramp_delay <= 25000)
 		control = MAX8973_RAMP_25mV_PER_US;
-		ret_val = 25000;
-	} else if (ramp_delay < 200000) {
+	else if (ramp_delay <= 50000)
 		control = MAX8973_RAMP_50mV_PER_US;
-		ret_val = 50000;
-	} else {
+	else if (ramp_delay <= 200000)
 		control = MAX8973_RAMP_200mV_PER_US;
-		ret_val = 200000;
-	}
+	else
+		return -EINVAL;
 
 	ret = regmap_update_bits(max->regmap, MAX8973_CONTROL1,
 			MAX8973_RAMP_MASK, control);
-- 
2.8.1