From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [PATCH] libfdt: add address translation support Date: Mon, 12 May 2014 16:10:02 +1000 Message-ID: <1399875002.17624.89.camel@pasglop> References: <1396371463-7516-1-git-send-email-robherring2@gmail.com> <20140512060000.GA28789@voom> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140512060000.GA28789@voom> Sender: devicetree-compiler-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: David Gibson Cc: Grant Likely , Rob Herring , devicetree-compiler-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Rob Herring , Scott Wood , Kim Phillips , Kumar Gala On Mon, 2014-05-12 at 16:00 +1000, David Gibson wrote: > I'm not all that impressed by this translation code - in particular > the per-bus-type hooks don't make sense to me. AFAIK the > interpretation of ranges is not bus specific. I think it will also > fail in some cases with #address-cells > 2, which is unfortunate. > > I'm about to post my own implementation of address translation. Well, I came up with the original code which did per-bus type hooks. There are cases where it is needed. Take PCI. The top word can contain completely unrelated stuff such as the "prefetchable" attribute. It's perfectly legal to put a prefetchable BAR under a non-prefetchable bridge window. However a translation scheme that doesn't know to know that bit will fail. It's not far fetched, it happens on our machines today. And that's just one of the problems I had back then... Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe devicetree-compiler" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html