On Mon, Sep 07, 2020 at 02:06:15PM +0200, Bartosz Golaszewski wrote: > On Mon, Sep 7, 2020 at 1:53 PM Andy Shevchenko > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote: > > On Mon, Sep 07, 2020 at 12:26:34PM +0200, Bartosz Golaszewski wrote: > > > On Mon, Sep 7, 2020 at 11:59 AM Andy Shevchenko > > > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote: > > > > On Fri, Sep 04, 2020 at 08:15:59PM -0700, Randy Dunlap wrote: > > > > > On 9/4/20 8:45 AM, Bartosz Golaszewski wrote: ... > > > > > > +GPIO Testing Driver > > > > > > +=================== > > > > > > + > > > > > > +The GPIO Testing Driver (gpio-mockup) provides a way to create simulated GPIO > > > > > > +chips for testing purposes. There are two ways of configuring the chips exposed > > > > > > +by the module. The lines can be accessed using the standard GPIO character > > > > > > +device interface as well as manipulated using the dedicated debugfs directory > > > > > > +structure. > > > > > > > > > > Could configfs be used for this instead of debugfs? > > > > > debugfs is ad hoc. > > > > > > > > Actually sounds like a good idea. > > > > > > > > > > Well, then we can go on and write an entirely new mockup driver > > > (ditching module params and dropping any backwards compatibility) > > > because we're already using debugfs for line values. > > > > > > How would we pass the device properties to configfs created GPIO chips > > > anyway? Devices seem to only be created using mkdir. Am I missing > > > something? > > > > Same way how USB composite works, no? > > > > OK, so create a new chip directory in configfs, configure it using > some defined configfs attributes and then finally instantiate it from > sysfs? > > Makes sense and is probably the right way to go. Now the question is: > is it fine to just entirely remove the previous gpio-mockup? Since, for example, I never saw device property bindings for that driver I assume that it was never considered as an ABI, so feel free to hack it in either direction. > Should we > keep some backwards compatibility? I wouldn't probably spend time on this. > Should we introduce an entirely new > module and have a transition period before removing previous > gpio-mockup? Neither transition period. > Also: this is a testing module so to me debugfs is just fine. Is > configfs considered stable ABI like sysfs? But this one is a good question. I think ConfigFS is stricter than DebugFS, up to being an ABI. But never did myself such a thing, so would like to hear experienced developers. -- With Best Regards, Andy Shevchenko
