Re: [PATCH 3/4] rtc: Introduce devm_rtc_allocate_device_priv

[Dan Carpenter <dan.carpenter@linaro.org>]

On Tue, Jan 21, 2025 at 02:35:59PM +0000, Peng Fan wrote:
> Hi Dan,
> 
> > Subject: Re: [PATCH 3/4] rtc: Introduce devm_rtc_allocate_device_priv
> > 
> > On Mon, Jan 20, 2025 at 10:25:35AM +0800, Peng Fan (OSS) wrote:
> > >  int __devm_rtc_register_device(struct module *owner, struct
> > > rtc_device *rtc) diff --git a/drivers/rtc/dev.c b/drivers/rtc/dev.c
> > > index
> > >
> > c4a3ab53dcd4b7280a3a2981fe842729603a1feb..e0e1a488b795645d
> > 7c9453490d6c
> > > dba510cc5db5 100644
> > > --- a/drivers/rtc/dev.c
> > > +++ b/drivers/rtc/dev.c
> > > @@ -410,7 +410,8 @@ static long rtc_dev_ioctl(struct file *file,
> > >  		}
> > >  		default:
> > >  			if (rtc->ops->param_get)
> > > -				err = rtc->ops->param_get(rtc-
> > >dev.parent, &param);
> > > +				err = rtc->ops->param_get(rtc->priv ?
> > > +							  &rtc->dev :
> > rtc->dev.parent, &param);
> > 
> > This seems kind of horrible...  I can't think of anywhere else which does
> > something like this.
> > 
> > It would almost be better to do something like:
> > 
> > 	err = rtc->ops->param_get(rtc->priv ? (void *)rtc : rtc-
> > >dev.parent, &param);
> > 
> > The advatange of this is that it looks totally horrible from the get go
> > instead of only subtly wrong.  And it would immediately crash if you
> > got it wrong implementing the ->param_get() function pointer.
> 
> Thanks for help improving the code. I will include this in V2 and post
> out after we reach a goal on how to support the 2nd RTC on i.MX95.

Don't do what I said actually...  Let's find a better way.  I don't
know why rtc_class_ops function pointers take a device pointer instead
of an rtc_device pointer.  Or if they did take a device pointer why
not the &rtc->dev like you suggested?  But let's not do both like this.

Migrating all the function pointers is a lot of work but not impossible.

regards,
dan carpenter