RE: [PATCH] HID: sony: Add touchpad support for Sony's NSG-MR5U and NSG-MR7U remotes

[Jiri Kosina <jikos@kernel.org>]

On Wed, 22 Mar 2017, Colenbrander, Roelof wrote:

> On a sidenote I'm starting to wonder how we should deal with multiple 
> devices in this driver in the future. The driver is starting to support 
> many different kinds of devices (mostly game controllers) and a few 
> other devices (vaio). They are all HID, but behave very differently and 
> some share concepts e.g. LEDs, touchpads or motion sensors. It is 
> starting to become more and more painful to handle many very different 
> devices in kind of one driver even though they are not really related. 
> There are layers of abstractions to dispatch to the right 'subdriver' 
> e.g. in sony_raw_event and many other places. There is a shared driver 
> structure (sony_sc), but some portions like function pointers or work 
> structs only apply to some devices.

If this is going to become a real problem, the most straightforward 
solution to me would be to actually separate the driver into completely 
different 'sub-drivers', but have them link at the end of the day into one 
'hid-sony', mostly for compatibility reasons (but also to keep following 
the general pattern we have).

> Also thinking a bit in how to use this driver in actual products. We may 
> only want certain pieces (e.g. game controller support) and not support 
> for the other devices either because we already have another driver for 
> it or we don't want to include this code as we don't intend to support 
> it (and verify behaviour) on said product. It is in nobody's interest to 
> have multiple code bases.

You can always blacklist/unbind the device if you're going to ship some 
out-of-tree driver, but I don't think we should really optimize the 
in-kernel code for that.

Thanks,

-- 
Jiri Kosina
SUSE Labs