2011-06-21 03:39:35

by Tushar Behera

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

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 <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: MyungJoo Ham <[email protected]>
Cc: Kyungmin Park <[email protected]>
Cc: Samuel Ortiz <[email protected]>
Signed-off-by: Tushar Behera <[email protected]>
---
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

2011-06-21 10:08:48

by Mark Brown

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

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 <[email protected]>

2011-06-22 02:49:07

by MyungJoo Ham

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

Sender : Tushar Behera<[email protected]>
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 <[email protected]>

> ---
> 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 (?Ը???)
Mobile Software Platform Lab,
Digital Media and Communications (DMC) Business
Samsung Electronics
cell: +82-10-6714-2858 / office: +82-31-279-8033????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m????????????I?

2011-06-22 03:23:08

by Tushar Behera

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

On Wednesday 22 June 2011 08:18 AM, ?Ը??? wrote:
> Sender : Tushar Behera<[email protected]>
> 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<[email protected]>
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 (?Ը???)
> Mobile Software Platform Lab,
> Digital Media and Communications (DMC) Business
> Samsung Electronics
> cell: +82-10-6714-2858 / office: +82-31-279-8033


--
Tushar Behera