2019-10-16 14:50:26

by Chuhong Yuan

Subject: [PATCH] media: st-mipid02: add a check for devm_gpiod_get_optional

mipid02_probe misses a check for devm_gpiod_get_optional and may miss
the failure.
Add a check to fix the problem.

Signed-off-by: Chuhong Yuan <[email protected]>
---
drivers/media/i2c/st-mipid02.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/media/i2c/st-mipid02.c b/drivers/media/i2c/st-mipid02.c
index 81285b8d5cfb..d38e888b0a43 100644
--- a/drivers/media/i2c/st-mipid02.c
+++ b/drivers/media/i2c/st-mipid02.c
@@ -971,6 +971,9 @@ static int mipid02_probe(struct i2c_client *client)
bridge->reset_gpio = devm_gpiod_get_optional(dev, "reset",
GPIOD_OUT_HIGH);

+ if (IS_ERR(bridge->reset_gpio))
+ return PTR_ERR(bridge->reset_gpio);
+
ret = mipid02_get_regulators(bridge);
if (ret) {
dev_err(dev, "failed to get regulators %d", ret);
--
2.20.1

2019-10-18 09:42:18

by Mickael GUENE

Subject: Re: [PATCH] media: st-mipid02: add a check for devm_gpiod_get_optional

Hello Chuhong,

Is this check necessary ?
since looking into code it seems to me devm_gpiod_get_optional() can only
return NULL in case of error due to following check in devm_gpiod_get_index_optional()
if (IS_ERR(desc)) {
if (PTR_ERR(desc) == -ENOENT)
return NULL;
}
And in that case reset_gpio is not used

Regards
Mickael

On 10/16/19 12:56, Chuhong Yuan wrote:
> mipid02_probe misses a check for devm_gpiod_get_optional and may miss
> the failure.
> Add a check to fix the problem.
>
> Signed-off-by: Chuhong Yuan <[email protected]>
> ---
> drivers/media/i2c/st-mipid02.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/media/i2c/st-mipid02.c b/drivers/media/i2c/st-mipid02.c
> index 81285b8d5cfb..d38e888b0a43 100644
> --- a/drivers/media/i2c/st-mipid02.c
> +++ b/drivers/media/i2c/st-mipid02.c
> @@ -971,6 +971,9 @@ static int mipid02_probe(struct i2c_client *client)
> bridge->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> GPIOD_OUT_HIGH);
>
> + if (IS_ERR(bridge->reset_gpio))
> + return PTR_ERR(bridge->reset_gpio);
> +
> ret = mipid02_get_regulators(bridge);
> if (ret) {
> dev_err(dev, "failed to get regulators %d", ret);
>

2019-10-18 10:14:11

by Chuhong Yuan

Subject: Re: [PATCH] media: st-mipid02: add a check for devm_gpiod_get_optional

On Thu, Oct 17, 2019 at 1:43 PM Mickael GUENE <[email protected]> wrote:
>
> Hello Chuhong,
>
> Is this check necessary ?
> since looking into code it seems to me devm_gpiod_get_optional() can only
> return NULL in case of error due to following check in devm_gpiod_get_index_optional()
> if (IS_ERR(desc)) {
> if (PTR_ERR(desc) == -ENOENT)
> return NULL;
> }
> And in that case reset_gpio is not used
>

The problem may not be a null return value, but a returned error,
which is a minus value,
like -EPROBE_DEFER or -EINVAL returned by gpiod_find in gpiod_get_index.
In these cases, devm_gpiod_get_index_optional will not return null but
return the error.
Therefore, this check is necessary.

> Regards
> Mickael
>
> On 10/16/19 12:56, Chuhong Yuan wrote:
> > mipid02_probe misses a check for devm_gpiod_get_optional and may miss
> > the failure.
> > Add a check to fix the problem.
> >
> > Signed-off-by: Chuhong Yuan <[email protected]>
> > ---
> > drivers/media/i2c/st-mipid02.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/media/i2c/st-mipid02.c b/drivers/media/i2c/st-mipid02.c
> > index 81285b8d5cfb..d38e888b0a43 100644
> > --- a/drivers/media/i2c/st-mipid02.c
> > +++ b/drivers/media/i2c/st-mipid02.c
> > @@ -971,6 +971,9 @@ static int mipid02_probe(struct i2c_client *client)
> > bridge->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> > GPIOD_OUT_HIGH);
> >
> > + if (IS_ERR(bridge->reset_gpio))
> > + return PTR_ERR(bridge->reset_gpio);
> > +
> > ret = mipid02_get_regulators(bridge);
> > if (ret) {
> > dev_err(dev, "failed to get regulators %d", ret);
> >

2019-10-18 15:47:27

by Mickael GUENE

Subject: Re: [PATCH] media: st-mipid02: add a check for devm_gpiod_get_optional

Hello Chuhong,

Sorry I missed 'if (PTR_ERR(desc) == -ENOENT)' check ....
Can you in this case add an error message ?

Regards
Mickael

On 10/17/19 09:48, Chuhong Yuan wrote:
> On Thu, Oct 17, 2019 at 1:43 PM Mickael GUENE <[email protected]> wrote:
>>
>> Hello Chuhong,
>>
>> Is this check necessary ?
>> since looking into code it seems to me devm_gpiod_get_optional() can only
>> return NULL in case of error due to following check in devm_gpiod_get_index_optional()
>> if (IS_ERR(desc)) {
>> if (PTR_ERR(desc) == -ENOENT)
>> return NULL;
>> }
>> And in that case reset_gpio is not used
>>
>
> The problem may not be a null return value, but a returned error,
> which is a minus value,
> like -EPROBE_DEFER or -EINVAL returned by gpiod_find in gpiod_get_index.
> In these cases, devm_gpiod_get_index_optional will not return null but
> return the error.
> Therefore, this check is necessary.
>
>> Regards
>> Mickael
>>
>> On 10/16/19 12:56, Chuhong Yuan wrote:
>>> mipid02_probe misses a check for devm_gpiod_get_optional and may miss
>>> the failure.
>>> Add a check to fix the problem.
>>>
>>> Signed-off-by: Chuhong Yuan <[email protected]>
>>> ---
>>> drivers/media/i2c/st-mipid02.c | 3 +++
>>> 1 file changed, 3 insertions(+)
>>>
>>> diff --git a/drivers/media/i2c/st-mipid02.c b/drivers/media/i2c/st-mipid02.c
>>> index 81285b8d5cfb..d38e888b0a43 100644
>>> --- a/drivers/media/i2c/st-mipid02.c
>>> +++ b/drivers/media/i2c/st-mipid02.c
>>> @@ -971,6 +971,9 @@ static int mipid02_probe(struct i2c_client *client)
>>> bridge->reset_gpio = devm_gpiod_get_optional(dev, "reset",
>>> GPIOD_OUT_HIGH);
>>>
>>> + if (IS_ERR(bridge->reset_gpio))
>>> + return PTR_ERR(bridge->reset_gpio);
>>> +
>>> ret = mipid02_get_regulators(bridge);
>>> if (ret) {
>>> dev_err(dev, "failed to get regulators %d", ret);
>>>