From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Subject: Re: irqchip heirarchy DT "break" series awareness? Date: Tue, 07 Apr 2015 11:21:35 +0100 Message-ID: <5523AFAF.6040000@arm.com> References: <20150406144647.GC7873@io.lakedaemon.net> <20150407115922.5d4c6233@free-electrons.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150407115922.5d4c6233-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thomas Petazzoni , Jason Cooper Cc: Arnd Bergmann , Olof Johansson , "arm-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Thomas Gleixner , Linux ARM Kernel List-Id: devicetree@vger.kernel.org Hi Thomas, On 07/04/15 10:59, Thomas Petazzoni wrote: > But the point of the slides stand: even for a piece of hardware as > well-documented as the GIC, as widely used as the GIC, with as many > bright and smart engineers looking into it, the community has not been > able to put out a DT binding that can be kept stable. How can we expect > such a DT binding stability to occur for undocumented hardware, or > SoC-specific hardware blocks that are definitely a lot less used than > the GIC ? The problem at hand is not so much the GIC itself, but the fact that only the GIC was described in DT. The GIC binding is unchanged, but some additional hardware is now described. If the relationship between the GIC and the shadow interrupt controllers had been described, we would have avoided breaking the compatibility. I guess it was too tempting to reuse pre-DT mechanisms and to forget about this entirely. Thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Tue, 07 Apr 2015 11:21:35 +0100 Subject: irqchip heirarchy DT "break" series awareness? In-Reply-To: <20150407115922.5d4c6233@free-electrons.com> References: <20150406144647.GC7873@io.lakedaemon.net> <20150407115922.5d4c6233@free-electrons.com> Message-ID: <5523AFAF.6040000@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Thomas, On 07/04/15 10:59, Thomas Petazzoni wrote: > But the point of the slides stand: even for a piece of hardware as > well-documented as the GIC, as widely used as the GIC, with as many > bright and smart engineers looking into it, the community has not been > able to put out a DT binding that can be kept stable. How can we expect > such a DT binding stability to occur for undocumented hardware, or > SoC-specific hardware blocks that are definitely a lot less used than > the GIC ? The problem at hand is not so much the GIC itself, but the fact that only the GIC was described in DT. The GIC binding is unchanged, but some additional hardware is now described. If the relationship between the GIC and the shadow interrupt controllers had been described, we would have avoided breaking the compatibility. I guess it was too tempting to reuse pre-DT mechanisms and to forget about this entirely. Thanks, M. -- Jazz is not dead. It just smells funny...