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regulator: MAX8997: Fix for divide by zero error

PATCH 함명주 2 participants 2 messages Jun 22, 2011

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함명주

author Acked-by
#0 lore raw

Sender : Tushar Behera<[email protected]>
Date : 2011-06-21 12:38 (GMT+09:00)

Quoted 7 lines

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.

Quoted 6 lines
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]>
Quoted 28 lines

---
drivers/regulator/max8997.c | 8 ++++----

1 files changed, 4 insertions(+), 4 deletions(-)
drivers/regulator/max8997.c +4 -4
index 10d5a1d..0fc7b8c 100644
@@ -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;
Quoted 6 lines

err:
for (i = 0; i < max8997->num_regulators; i++)

Signature · 1 line
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�淸�{.n�+돴윯돪�+%듚�깁負쪐w��{.n�+돴쪐{깸G쳺��{ay����,j�f＂톒쉹��묎�z_溫(�쉸듶줷"얎�m����G쳺�◀?솳鈺�&ｘ�~뤳턨O뺞촾퇉v�^�m��� �띠�◀?뻀�

#1 lore raw
Quoted 9 lines · 함명주

Sender : Tushar Behera<[email protected]>
Date : 2011-06-21 12:38 (GMT+09:00)

Quoted 7 lines

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.

Quoted 8 lines
Quoted 6 lines
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)

Quoted 2 lines
Acked-by MyungJoo Ham<[email protected]>

Thanks.

Quoted 1 line

<snipped>

Quoted 42 lines
Quoted 28 lines

---
drivers/regulator/max8997.c | 8 ++++----

1 files changed, 4 insertions(+), 4 deletions(-)
drivers/regulator/max8997.c +4 -4
index 10d5a1d..0fc7b8c 100644
@@ -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;
Quoted 6 lines

err:
for (i = 0; i< max8997->num_regulators; i++)

Signature · 1 line
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

Signature · 1 line
Tushar Behera