[PATCH] regulator: MAX8997: Fix for divide by zero error

[PATCH] regulator: MAX8997: Fix for divide by zero error

[Tushar Behera]

Currently, ramp_delay variable is used uninitialzed in
max8997_set_voltage_ldobuck which gets called through
regulator_register calls.

To fix the problem, in max8997_pmic_probe, ramp_delay initialization
code is moved before calls to regulator_register.

Cc: Liam Girdwood <lrg@ti.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: MyungJoo Ham <myungjoo.ham@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
---
 drivers/regulator/max8997.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/regulator/max8997.c b/drivers/regulator/max8997.c
index 10d5a1d..0fc7b8c 100644
--- a/drivers/regulator/max8997.c
+++ b/drivers/regulator/max8997.c
@@ -1124,6 +1124,10 @@ static __devinit int max8997_pmic_probe(struct platform_device *pdev)
 				0x3f);
 	}
 
+	/* Misc Settings */
+	max8997->ramp_delay = 10; /* set 10mV/us, which is the default */
+	max8997_write_reg(i2c, MAX8997_REG_BUCKRAMP, (0xf << 4) | 0x9);
+
 	for (i = 0; i < pdata->num_regulators; i++) {
 		const struct voltage_map_desc *desc;
 		int id = pdata->regulators[i].id;
@@ -1148,10 +1152,6 @@ static __devinit int max8997_pmic_probe(struct platform_device *pdev)
 		}
 	}
 
-	/* Misc Settings */
-	max8997->ramp_delay = 10; /* set 10mV/us, which is the default */
-	max8997_write_reg(i2c, MAX8997_REG_BUCKRAMP, (0xf << 4) | 0x9);
-
 	return 0;
 err:
 	for (i = 0; i < max8997->num_regulators; i++)
-- 
1.7.4.1

Re: [PATCH] regulator: MAX8997: Fix for divide by zero error

[Mark Brown]

On Tue, Jun 21, 2011 at 09:08:59AM +0530, Tushar Behera wrote:
> Currently, ramp_delay variable is used uninitialzed in
> max8997_set_voltage_ldobuck which gets called through
> regulator_register calls.

> To fix the problem, in max8997_pmic_probe, ramp_delay initialization
> code is moved before calls to regulator_register.

Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

Re: [PATCH] regulator: MAX8997: Fix for divide by zero error

[함명주]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=euc-kr, Size: 2016 bytes --]

Sender : Tushar Behera<tushar.behera@linaro.org>
Date : 2011-06-21 12:38 (GMT+09:00)
> Currently, ramp_delay variable is used uninitialzed in
> max8997_set_voltage_ldobuck which gets called through
> regulator_register calls.
> 
> To fix the problem, in max8997_pmic_probe, ramp_delay initialization
> code is moved before calls to regulator_register.
> 
> Cc: Liam Girdwood 
> Cc: Mark Brown 
> Cc: MyungJoo Ham 
> Cc: Kyungmin Park 
> Cc: Samuel Ortiz 
> Signed-off-by: Tushar Behera 

Although I've never been reported such an issue, but I'm sure this will cause one any time. Thanks!

Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>

> ---
> drivers/regulator/max8997.c |    8 ++++----
> 1 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/regulator/max8997.c b/drivers/regulator/max8997.c
> index 10d5a1d..0fc7b8c 100644
> --- a/drivers/regulator/max8997.c
> +++ b/drivers/regulator/max8997.c
> @@ -1124,6 +1124,10 @@ static __devinit int max8997_pmic_probe(struct platform_device *pdev)
> 0x3f);
> }
> 
> + /* Misc Settings */
> + max8997->ramp_delay = 10; /* set 10mV/us, which is the default */
> + max8997_write_reg(i2c, MAX8997_REG_BUCKRAMP, (0xf << 4) | 0x9);
> +
> for (i = 0; i < pdata->num_regulators; i++) {
> const struct voltage_map_desc *desc;
> int id = pdata->regulators[i].id;
> @@ -1148,10 +1152,6 @@ static __devinit int max8997_pmic_probe(struct platform_device *pdev)
> }
> }
> 
> - /* Misc Settings */
> - max8997->ramp_delay = 10; /* set 10mV/us, which is the default */
> - max8997_write_reg(i2c, MAX8997_REG_BUCKRAMP, (0xf << 4) | 0x9);
> -
> return 0;
> err:
> for (i = 0; i < max8997->num_regulators; i++)
> -- 
> 1.7.4.1
> 
> 



 MyungJoo Ham (ÇÔ¸íÁÖ)
Mobile Software Platform Lab,
Digital Media and Communications (DMC) Business
Samsung Electronics
cell: +82-10-6714-2858 / office: +82-31-279-8033ÿôèº{.nÇ+‰·Ÿ®‰­†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a­¢f£¢·hšïêÿ‘êçz_è®\x03(­éšŽŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨è­Ú&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥

Re: [PATCH] regulator: MAX8997: Fix for divide by zero error

[Tushar Behera]

On Wednesday 22 June 2011 08:18 AM, 함명주 wrote:
> Sender : Tushar Behera<tushar.behera@linaro.org>
> Date : 2011-06-21 12:38 (GMT+09:00)
>> Currently, ramp_delay variable is used uninitialized in
>> max8997_set_voltage_ldobuck which gets called through
>> regulator_register calls.
>>
>> To fix the problem, in max8997_pmic_probe, ramp_delay initialization
>> code is moved before calls to regulator_register.
>>
>> Cc: Liam Girdwood
>> Cc: Mark Brown
>> Cc: MyungJoo Ham
>> Cc: Kyungmin Park
>> Cc: Samuel Ortiz
>> Signed-off-by: Tushar Behera
> 
> Although I've never been reported such an issue, but I'm sure this will cause one any time. Thanks!
One scenario:
Division by zero in kernel.
[<c00399c4>] (unwind_backtrace+0x0/0xe0) from [<c0162ed4>] (Ldiv0+0x8/0x10)
[<c0162ed4>] (Ldiv0+0x8/0x10) from [<c018a1bc>]
(max8997_set_voltage_ldobuck+0x198/0x1bc)
[<c018a1bc>] (max8997_set_voltage_ldobuck+0x198/0x1bc) from [<c0187ae8>]
(_regulator_do_set_voltage+0x2c/0x1c4)
[<c0187ae8>] (_regulator_do_set_voltage+0x2c/0x1c4) from [<c0187eec>]
(regulator_register+0x25c/0xe2c)
[<c0187eec>] (regulator_register+0x25c/0xe2c) from [<c02b9124>]
(max8997_pmic_probe+0x5b8/0x69c)
> 
> Acked-by: MyungJoo Ham<myungjoo.ham@samsung.com>
Thanks.
> 
<snipped>

>> ---
>> drivers/regulator/max8997.c |    8 ++++----
>> 1 files changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/regulator/max8997.c b/drivers/regulator/max8997.c
>> index 10d5a1d..0fc7b8c 100644
>> --- a/drivers/regulator/max8997.c
>> +++ b/drivers/regulator/max8997.c
>> @@ -1124,6 +1124,10 @@ static __devinit int max8997_pmic_probe(struct platform_device *pdev)
>> 0x3f);
>> }
>>
>> + /* Misc Settings */
>> + max8997->ramp_delay = 10; /* set 10mV/us, which is the default */
>> + max8997_write_reg(i2c, MAX8997_REG_BUCKRAMP, (0xf<<  4) | 0x9);
>> +
>> for (i = 0; i<  pdata->num_regulators; i++) {
>> const struct voltage_map_desc *desc;
>> int id = pdata->regulators[i].id;
>> @@ -1148,10 +1152,6 @@ static __devinit int max8997_pmic_probe(struct platform_device *pdev)
>> }
>> }
>>
>> - /* Misc Settings */
>> - max8997->ramp_delay = 10; /* set 10mV/us, which is the default */
>> - max8997_write_reg(i2c, MAX8997_REG_BUCKRAMP, (0xf<<  4) | 0x9);
>> -
>> return 0;
>> err:
>> for (i = 0; i<  max8997->num_regulators; i++)
>> -- 
>> 1.7.4.1
>>
>>
> 
> 
> 
>   MyungJoo Ham (함명주)
> Mobile Software Platform Lab,
> Digital Media and Communications (DMC) Business
> Samsung Electronics
> cell: +82-10-6714-2858 / office: +82-31-279-8033


-- 
Tushar Behera

Re: [PATCH] regulator: MAX8997: Fix for divide by zero error

[Liam Girdwood]

On Tue, 2011-06-21 at 09:08 +0530, Tushar Behera wrote:
> Currently, ramp_delay variable is used uninitialzed in
> max8997_set_voltage_ldobuck which gets called through
> regulator_register calls.
> 
> To fix the problem, in max8997_pmic_probe, ramp_delay initialization
> code is moved before calls to regulator_register.
> 
> Cc: Liam Girdwood <lrg@ti.com>
> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
> Cc: MyungJoo Ham <myungjoo.ham@samsung.com>
> Cc: Kyungmin Park <kyungmin.park@samsung.com>
> Cc: Samuel Ortiz <sameo@linux.intel.com>
> Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
> ---
>  drivers/regulator/max8997.c |    8 ++++----
>  1 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/regulator/max8997.c b/drivers/regulator/max8997.c
> index 10d5a1d..0fc7b8c 100644
> --- a/drivers/regulator/max8997.c
> +++ b/drivers/regulator/max8997.c
> @@ -1124,6 +1124,10 @@ static __devinit int max8997_pmic_probe(struct platform_device *pdev)
>  				0x3f);
>  	}
>  
> +	/* Misc Settings */
> +	max8997->ramp_delay = 10; /* set 10mV/us, which is the default */
> +	max8997_write_reg(i2c, MAX8997_REG_BUCKRAMP, (0xf << 4) | 0x9);
> +
>  	for (i = 0; i < pdata->num_regulators; i++) {
>  		const struct voltage_map_desc *desc;
>  		int id = pdata->regulators[i].id;
> @@ -1148,10 +1152,6 @@ static __devinit int max8997_pmic_probe(struct platform_device *pdev)
>  		}
>  	}
>  
> -	/* Misc Settings */
> -	max8997->ramp_delay = 10; /* set 10mV/us, which is the default */
> -	max8997_write_reg(i2c, MAX8997_REG_BUCKRAMP, (0xf << 4) | 0x9);
> -
>  	return 0;
>  err:
>  	for (i = 0; i < max8997->num_regulators; i++)

Applied.

Thanks

Liam