Re: [PATCH 1/3] drivers: misc: ak8974 / ami305 magnetometer driver

Onkalo Samu
2010-08-30T07:12:41Z

Hi Sundar,

On Sat, 2010-08-28 at 18:10 +0200, ext Sundar wrote:
> Hi Samu,
>
> few minor comments,
>
> On Fri, Aug 27, 2010 at 5:24 PM, Samu Onkalo <samu.p.onkalo-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org> wrote:
> > +
> > +struct ak8974_chip {
> > + struct miscdevice miscdev;
> > + struct mutex lock; /* Serialize access to chip */
> > + struct mutex users_lock;
> > + struct i2c_client *client;
> > + struct regulator_bulk_data regs[2];
> > + struct work_struct work;
> > + wait_queue_head_t misc_wait;
> > + loff_t offset;
> > +
> > + int max_range;
> > + int users;
> > +
> > + const char *id;
> > + u8 info[2];
> > +
> > + s16 x, y, z; /* Latest measurements */
> > + s8 axis_x;
> > + s8 axis_y;
> > + s8 axis_z;
> > + bool valid;
> > +
> > + char name[20];
> > +};
>
> This can be static ?

It is filled based on the detected chip type.

>
> > +
> > + ak8974_regulators_off(chip);
> > +
>
> [..]
>
> > + if (err < 0) {
> > + dev_err(&chip->client->dev, "Device registration failed\n");
> > + goto fail3;
> > + }
>
> [..]
>
> > + return 0;
> > +fail4:
> > + misc_deregister(&chip->miscdev);
> > +fail3:
> > + ak8974_regulators_off(chip);
>
> in case of fail3, regulators get disabled twice. i think we will have
> unbalanced calls to the supplies then.
>

Yes, you are correct.

> > +
> > +
> > +#ifdef CONFIG_PM
> > +static int ak8974_suspend(struct i2c_client *client, pm_message_t mesg)
> > +{
> > + struct ak8974_chip *chip = i2c_get_clientdata(client);
> > + mutex_lock(&chip->users_lock);
> > + if (chip->users > 0)
> > + ak8974_enable(chip, AK8974_PWR_OFF);
> > + mutex_unlock(&chip->users_lock);
> > + return 0;
> > +}
>
> Can we disable the regulators here too?

It would require some more operations since the chip would loose its
state totally. But yes, it could be done.

-Samu