2014-10-28 3:13 GMT+03:00 Russell King - ARM Linux [off-list ref]:

On Tue, Oct 28, 2014 at 03:01:53AM +0300, Dmitry Eremin-Solenikov wrote:

quoted

Sharp Zaurus SL-5500 and SL-5600 use special companion Gate Array. Current
drivers present in Linux kernel has some problems:

 * It uses custom bus instead of platform bus/mfd core.

I believe Greg wouldn't see that as a positive point.

Don't think that the platform bus _should_ always be used.  It shouldn't
(Greg has said he'd like to see the platform bus to be totally killed off.)
Instead, custom buses properly suited to the class of device in question
is much preferred, especially if it aids in...

Greg, Russell, what should I use then for mfd multi-cell devices?
Is mfd-core still a permitted API? Should we change mfd-core
internals to spawn extra bus (busses?) for the cells?

quoted

 * Device drivers are not well layered/separated.

... better layering or separation of drivers.

So, thinking that converting from a custom bus to a platform bus
definitely is /not/ a positive step forward.

-- 
With best wishes
Dmitry