[alsa-devel] [PATCH 12/19] twl4030: mfd_cell is now implicitly available to drivers

[Andres Salomon]

On Wed, 2 Feb 2011 22:05:21 -0800
Dmitry Torokhov <dmitry.torokhov at gmail.com> wrote:

> On Wed, Feb 02, 2011 at 08:15:22PM -0800, Andres Salomon wrote:
> >  static int __devinit twl4030_vibra_probe(struct platform_device
> > *pdev) {
> > -	struct twl4030_codec_vibra_data *pdata =
> > pdev->dev.platform_data;
> > +	struct twl4030_codec_vibra_data *pdata =
> > platform_get_drvdata(pdev);
> 
> No, device's drvdata belongs to _this_ driver, and it is supposed to
> manage it and use as it sees fit.

Right, so it's used to pass data to the probe function; once the probe
function has obtained the pdata pointer, it's free to do with it what
it will.


> 
> Note platform_set_drvdata(pdev, info) later in this function along
> with platform_set_drvdata(pdev, NULL) in twl4030_vibra_remove(),
> which means that with your change you will be able to bind the device
> only once.
> 

Hm, good point; if the driver is reloaded, the pdev that was created by
mfd-core will have lost the pointer to pdata.

I wonder if I should be using mfd's driver_data instead. I used
platform_data because a bunch of drivers had already made use of it to
pass cell information..