2017-09-04 15:01:04

by Dragos Bogdan

Subject: [PATCH] iio:ad7793: Fix the serial interface reset

The serial interface can be reset by writing 32 consecutive 1s to the device.
The value of 'ret' is overwritten when ad7793_check_platform_data() is called,
so it should be initialized to -1 only before doing the spi_write().

Fixes: commit 2edb769d246e ("iio:ad7793: Add support for the ad7798 and ad7799")

Signed-off-by: Dragos Bogdan <[email protected]>
---
drivers/iio/adc/ad7793.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad7793.c b/drivers/iio/adc/ad7793.c
index e6706a09e100..8680abf72dd2 100644
--- a/drivers/iio/adc/ad7793.c
+++ b/drivers/iio/adc/ad7793.c
@@ -257,7 +257,7 @@ static int ad7793_setup(struct iio_dev *indio_dev,
unsigned int vref_mv)
{
struct ad7793_state *st = iio_priv(indio_dev);
- int i, ret = -1;
+ int i, ret;
unsigned long long scale_uv;
u32 id;

@@ -266,6 +266,7 @@ static int ad7793_setup(struct iio_dev *indio_dev,
return ret;

/* reset the serial interface */
+ ret = -1;
ret = spi_write(st->sd.spi, (u8 *)&ret, sizeof(ret));
if (ret < 0)
goto out;
--
2.11.0

2017-09-04 15:26:59

by Jonathan Cameron

Subject: Re: [PATCH] iio:ad7793: Fix the serial interface reset

On Mon, 4 Sep 2017 18:00:48 +0300
Dragos Bogdan <[email protected]> wrote:

> The serial interface can be reset by writing 32 consecutive 1s to the device.
> The value of 'ret' is overwritten when ad7793_check_platform_data() is called,
> so it should be initialized to -1 only before doing the spi_write().
>
> Fixes: commit 2edb769d246e ("iio:ad7793: Add support for the ad7798 and ad7799")
>
> Signed-off-by: Dragos Bogdan <[email protected]>

Hi Dragos,

I'd prefer we introduced a separate variable. Using ret for this
is what got us into trouble in the first place.

Would you mind respining with that change?

Thanks,

Jonathan

> ---
> drivers/iio/adc/ad7793.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/adc/ad7793.c b/drivers/iio/adc/ad7793.c
> index e6706a09e100..8680abf72dd2 100644
> --- a/drivers/iio/adc/ad7793.c
> +++ b/drivers/iio/adc/ad7793.c
> @@ -257,7 +257,7 @@ static int ad7793_setup(struct iio_dev *indio_dev,
> unsigned int vref_mv)
> {
> struct ad7793_state *st = iio_priv(indio_dev);
> - int i, ret = -1;
> + int i, ret;
> unsigned long long scale_uv;
> u32 id;
>
> @@ -266,6 +266,7 @@ static int ad7793_setup(struct iio_dev *indio_dev,
> return ret;
>
> /* reset the serial interface */
> + ret = -1;
> ret = spi_write(st->sd.spi, (u8 *)&ret, sizeof(ret));
> if (ret < 0)
> goto out;

2017-09-04 15:33:32

by Dragos Bogdan

Subject: Re: [PATCH] iio:ad7793: Fix the serial interface reset

On 09/04/2017 06:27 PM, Jonathan Cameron wrote:
> On Mon, 4 Sep 2017 18:00:48 +0300
> Dragos Bogdan <[email protected]> wrote:
>
>> The serial interface can be reset by writing 32 consecutive 1s to the device.
>> The value of 'ret' is overwritten when ad7793_check_platform_data() is called,
>> so it should be initialized to -1 only before doing the spi_write().
>>
>> Fixes: commit 2edb769d246e ("iio:ad7793: Add support for the ad7798 and ad7799")
>>
>> Signed-off-by: Dragos Bogdan <[email protected]>
> Hi Dragos,
>
> I'd prefer we introduced a separate variable. Using ret for this
> is what got us into trouble in the first place.
>
> Would you mind respining with that change?
>
> Thanks,
>
> Jonathan

Hi Jonathan,

I agree with your suggestion. I'll change it accordingly in v2.

Thanks,
Dragos

>> ---
>> drivers/iio/adc/ad7793.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/iio/adc/ad7793.c b/drivers/iio/adc/ad7793.c
>> index e6706a09e100..8680abf72dd2 100644
>> --- a/drivers/iio/adc/ad7793.c
>> +++ b/drivers/iio/adc/ad7793.c
>> @@ -257,7 +257,7 @@ static int ad7793_setup(struct iio_dev *indio_dev,
>> unsigned int vref_mv)
>> {
>> struct ad7793_state *st = iio_priv(indio_dev);
>> - int i, ret = -1;
>> + int i, ret;
>> unsigned long long scale_uv;
>> u32 id;
>>
>> @@ -266,6 +266,7 @@ static int ad7793_setup(struct iio_dev *indio_dev,
>> return ret;
>>
>> /* reset the serial interface */
>> + ret = -1;
>> ret = spi_write(st->sd.spi, (u8 *)&ret, sizeof(ret));
>> if (ret < 0)
>> goto out;
>
>