Re: cdev name generation

[Sascha Hauer <s.hauer@pengutronix.de>]

On Tue, Jan 18, 2011 at 09:22:20AM +1100, Marc Reilly wrote:
> Hi Sascha,
> 
> > > 
> > > Do you mean something like this attached patch?
> > 
> > Yes
> > 
> > > I preferred having the possibilty for assigning the id, so that boards
> > > can have some expectations of what the device name will be.
> > 
> > Generally a good idea, but how do you want to pass previd to the drivers
> > using it? via platform_data? I haven't looked into it to see if this
> > works well.
> > 
> 
> That's what I did for the at24, (although preferred_id would be a better name 
> than just id)
> 
> static struct at24_platform_data at24_data = {
> 	.size	= 2048 / 8,
> 	.id		= 1,
> };
> 
> 
> static int at24_probe(struct device_d *dev)
> {
> 	struct at24 *at24;
> 	struct at24_platform_data *pdata;
> 	at24 = xzalloc(sizeof(*at24));
> 
> 	dev->priv = at24;
> 	pdata = dev->platform_data;
> 
> 	at24->cdev.name = make_cdev_name("eeprom", pdata->id);
> 	at24->client = to_i2c_client(dev);
> 	at24->cdev.size = pdata->size;
> 	at24->cdev.dev = dev;
> 
> 
> Maybe the platform data should have the preferred cdev name also? In the 
> example above, the driver just blindly calls it "eeprom", ie a more generic 
> term than "at24", the driver name.
> If the desired end result is to have for example eeprom0, eeprom1 and eeprom2 
> cdevs all from potentially different drivers then I makes sense to also be 
> able to specify the "eeprom" part. (and then we'd probably want to pass in the 
> device_d* to make_cdev_name in case the user doesn't specify a cdev name - the 
> device name, and id, could be used).
> 
> Seems like too much thinking for so little code :)

I don't think so. This is one of the places where we'll regret a wrong
decision once we have to change it in the future and have to deal with
loads of breaking environments.

Sascha


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