Hi Jonathan,
On Sat, 15 Oct 2016 15:14:19 +0100
Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> On 11/10/16 14:57, Tomas Novotny wrote:
> > Signed-off-by: Tomas Novotny <tomas@xxxxxxxxxx>
> Few small bits inline.
>
> Jonathan
> > ---
> > drivers/iio/dac/mcp4725.c | 46 +++++++++++++++++++++++++++++++++++++++++-----
> > 1 file changed, 41 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/iio/dac/mcp4725.c b/drivers/iio/dac/mcp4725.c
> > index 29cf85d..b8954f2 100644
> > --- a/drivers/iio/dac/mcp4725.c
> > +++ b/drivers/iio/dac/mcp4725.c
> > @@ -19,6 +19,7 @@
> > #include <linux/err.h>
> > #include <linux/delay.h>
> > #include <linux/regulator/consumer.h>
> > +#include <linux/of.h>
> >
> > #include <linux/iio/iio.h>
> > #include <linux/iio/sysfs.h>
> > @@ -364,6 +365,30 @@ static const struct iio_info mcp4725_info = {
> > .driver_module = THIS_MODULE,
> > };
> >
> > +#ifdef CONFIG_OF
> > +static int mcp4725_probe_dt(struct device *dev,
> > + struct mcp4725_platform_data *pdata)
> > +{
> > + struct device_node *np = dev->of_node;
> > +
> > + if (!np)
> > + return -ENODEV;
> > +
> > + /* check if is the vref-supply defined */
> > + pdata->use_vref = of_property_read_bool(np, "vref-supply");
> > + pdata->vref_buffered =
> > + of_property_read_bool(np, "microchip,vref-buffered");
> > +
> > + return 0;
> > +}
> > +#else
> > +static int mcp4725_probe_dt(struct device *dev,
> > + struct mcp4725_platform_data *platform_data)
> > +{
> > + return -ENODEV;
> > +}
> > +#endif
> > +
> > static int mcp4725_probe(struct i2c_client *client,
> > const struct i2c_device_id *id)
> > {
> > @@ -375,11 +400,6 @@ static int mcp4725_probe(struct i2c_client *client,
> > u8 ref;
> > int err;
> >
> > - if (!pdata) {
> > - dev_err(&client->dev, "invalid platform data");
> > - return -EINVAL;
> > - }
> > -
> > indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> > if (indio_dev == NULL)
> > return -ENOMEM;
> > @@ -388,6 +408,19 @@ static int mcp4725_probe(struct i2c_client *client,
> > data->client = client;
> > data->id = id->driver_data;
> >
> > + if (!pdata) {
> May seem an odd way to do it, but I would use
> if (!dev_get_platdata(&client->dev)) so it's obvious what it matches
> against when it comes to unwinding this down below.
I will rewrite it completely, see below.
> > + pdata = devm_kzalloc(&client->dev, sizeof(*pdata), GFP_KERNEL);
> > + if (!pdata)
> > + return -ENOMEM;
> > +
> > + err = mcp4725_probe_dt(&client->dev, pdata);
> > + if (err) {
> > + dev_err(&client->dev,
> > + "invalid platform or devicetree data");
> > + return err;
> > + }
> > + }
> > +
> > if (data->id == MCP4725 && pdata->use_vref) {
> > dev_warn(&client->dev,
> > "ignoring unavailable external reference on MCP4725");
> > @@ -460,6 +493,9 @@ static int mcp4725_probe(struct i2c_client *client,
> > if (err)
> > goto err_disable_vref_reg;
> >
> > + if (!dev_get_platdata(&client->dev))
> > + devm_kfree(&client->dev, pdata);
> Hmm. I wonder if it's worth freeing this explicitly rather than just letting
> it clear up on driver remove. It seems odd to use devm allocations for
> what is a short term termporary variable.
>
> Actually why not just use a local variable on the stack and set
> pdata to point to that? Then your cleanup is all nice an automatic
> without having to do this slightly odd devm usage.
Well, you are right. I saw this construction somewhere else (in another
subsystem) but the local variable would be better.
Thanks for the review,
Tomas
> > +
> > return 0;
> >
> > err_disable_vref_reg:
> >
>
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