Re: [patch 1/2] Touchscreen support for sharp sl-5500

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On 7/25/05, Russell King <rmk+lkml@arm.linux.org.uk> wrote:
> On Mon, Jul 25, 2005 at 10:16:05AM -0500, Dmitry Torokhov wrote:
> > If the problem is that you have a single piece of hardware you need to
> > bind several drivers to - I guess you will have to create a new
> > sub-device bus for that. Or just register sub-devices on the same bus
> > the parent device is registered on - I am not sure what is best in
> > this particular case - I am not familiar with the arch.
> 
> That is exactly the problem - these kinds of devices do _not_ fit
> well into the device model.  A struct device for every different
> possible sub-unit is completely overkill.
> 
> For instance, you may logically use one ADC and some GPIO lines
> on the device for X and something else for Y and they logically
> end up in different drivers.
> 
> The problem is that the parent doesn't actually know how many
> devices to create nor what to call them, and they're logically
> indistinguishable from each other so there's no logical naming
> system.
> 

Then we should probably not try to force them into driver model. Have
parent device register struct device and when sub-drivers register
they could attach class devices (like input devices) directly to the
"main" device thus hiding presence of sub-sections of the chip from
sysfs completely. My point is that we should not be using
class_interface here - its purpose is diferent.

-- 
Dmitry