[RFC v3 08/13] ahci-platform: Allow specifying platform_data through of_device_id

[Russell King - ARM Linux]

On Sun, Jan 19, 2014 at 06:38:38AM -0500, Tejun Heo wrote:
> On Sun, Jan 19, 2014 at 12:48:50AM +0100, Hans de Goede wrote:
> > @@ -126,7 +151,7 @@ static void ahci_put_clks(struct ahci_host_priv *hpriv)
> >  static int ahci_probe(struct platform_device *pdev)
> >  {
> >  	struct device *dev = &pdev->dev;
> > -	struct ahci_platform_data *pdata = dev_get_platdata(dev);
> > +	const struct ahci_platform_data *pdata = ahci_get_pdata(dev);
> 
> Let's please not add const.  For data types which are known to be
> terminal, const more or less works, I suppose but for anything even
> mildly complicated it ends up being more of a headache.  C just
> doesn't have enough language support to make const actually useful.
> e.g. now if somebody wants to add an accessor to ahci_platform_data()
> which is applicable to both readers and writers, we either need two
> separate accessors for const and !const paths or have to cast away
> const.

I don't see anything wrong with this.  Platform data should _never_ be
written to, because doing so will change the driver behaviour between
bindings.  It really should be read-only to driver code.

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