From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Eremin-Solenikov Subject: Re: [PATCH 00/15] new locomo driver Date: Tue, 28 Oct 2014 04:28:53 +0400 Message-ID: References: <1414454528-24240-1-git-send-email-dbaryshkov@gmail.com> <20141028001338.GZ27405@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Greg KH , linux-arm-kernel , "linux-gpio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , linux-input , linux-leds , linux-spi , linux-fbdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org, Andrea Adami , Daniel Mack , Haojian Zhuang , Robert Jarzmik , Linus Walleij , Alexandre Courbot , Dmitry Torokhov , Bryan Wu , Richard Purdie , Samuel Ortiz , Lee Jones , Mark Brown , Jingoo Han , Liam Girdwood To: Russell King - ARM Linux Return-path: In-Reply-To: <20141028001338.GZ27405-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: 2014-10-28 4:13 GMT+04:00 Russell King - ARM Linux : > 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 I'm sorry, I must be outdated on this topic.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-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html