From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH 2/2] ARM: dts: USB for Tegra114 Dalmore Date: Wed, 31 Jul 2013 17:29:40 -0600 Message-ID: <51F99DE4.7010503@wwwdotorg.org> References: <1375292543-7896-1-git-send-email-ttynkkynen@nvidia.com> <1375292543-7896-3-git-send-email-ttynkkynen@nvidia.com> <51F9550F.3080503@cogentembedded.com> <51F9660C.6090604@iki.fi> <51F96B48.10209@cogentembedded.com> <51F98A78.9060309@wwwdotorg.org> <51F98D92.3010607@cogentembedded.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51F98D92.3010607-M4DtvfQ/ZS1MRgGoP+s0PdBPR1lH4CV8@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sergei Shtylyov Cc: Tuomas Tynkkynen , Tuomas Tynkkynen , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Mikko Perttunen List-Id: linux-tegra@vger.kernel.org On 07/31/2013 04:20 PM, Sergei Shtylyov wrote: > On 08/01/2013 02:06 AM, Stephen Warren wrote: ... >>> That's really horrible design. >> >> Yup. Both USB PHY and EHCI controller registers really are interleaved >> in one range. > > But the standard EHCI register space has no holes IIRC, so they can't > be really that much interleaved as you're describing (unless you have > some non-standard registers of course)... Yes, there are certainly non-standard registers. ... >>> Don't they cause numerous resource conflicts while device nodes >>> being >>> instantiated as the platform devices? > >> No; the driver knows that the HW is screwy and there's lots of >> register-range sharing going on, so it simply maps the registers, rather >> than reserving the physical address range and mapping it. > > Yes, it's clear that the driver should take special measures, I was > asking about the platform device creation phase. What do you see in > /proc/iomem? The drivers don't request the memory region since doing so would cause conflicts. Hence, the regions don't show up in /proc/iomem. This actually isn't that uncommon for DT-based drivers anyway; many use e.g. of_iomap() which IIRC just looks up the resource and maps it without registering the usage. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html