2014-10-28 4:13 GMT+04:00 Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>: > On Tue, Oct 28, 2014 at 03:01:53AM +0300, Dmitry Eremin-Solenikov wrote: >> 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... I'm sorry, I must be outdated on this topic. Few years ago things were exactly opposite - we explicitly had to use platform bus for mfd devices. I still think that mfd devices containing several cells should use mfd-core (is it still OK to use it?). And mfd-core (up to now) uses platform bus. > >> * 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. Is there an example of new approach? Current locomo-dev implementation is poisoned with several bugs. For example it passes ioremapped memory as resources to child devices that later call request_resource() on it. Adding additional features (like correct work with IRQs) will duplicate platform bus code and mfd functions. > > (Why mfd was ever allowed to re-use the platform bus stuff is a separate > question not relevent to these patches.) I remember this story - Ian Molton and me wrote mfd-core.c. -- With best wishes Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
