From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH] drm/i915: By default, enable RC6 on IVB and SNB when reasonable Date: Wed, 23 Nov 2011 21:35:42 +0100 Message-ID: <20111123203542.GI3864@phenom.ffwll.local> References: <1321684889-18691-1-git-send-email-keithp@keithp.com> <20111122201531.GD5547@srcf.ucam.org> <861uszfrah.fsf@sumi.keithp.com> <20111123102643.GB3864@phenom.ffwll.local> <1322056914.15493.158.camel@shinybook.infradead.org> <20111123143931.GE3864@phenom.ffwll.local> <1322060623.15493.168.camel@shinybook.infradead.org> <20111123154128.GG3864@phenom.ffwll.local> <1322062985.15493.176.camel@shinybook.infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1322062985.15493.176.camel@shinybook.infradead.org> Sender: linux-kernel-owner@vger.kernel.org To: David Woodhouse Cc: Daniel Vetter , rajesh.sankaran@intel.com, Keith Packard , Matthew Garrett , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Wed, Nov 23, 2011 at 03:43:05PM +0000, David Woodhouse wrote: > On Wed, 2011-11-23 at 16:41 +0100, Daniel Vetter wrote: > > Hm, that comment confuses me a bit. I've always thought that igfx_off only > > instantiates a identity mapping and leaves the dmar unit on. Is that > > wrong? > > It's completely off. If a DMAR unit has *only* graphics devices behind > it (as the one for the built-in graphics does, because it's a whole > boatload of speshul case for integration with the GTT), we just don't > enable it at all. See the second for_each_drhd_unit() loop in > init_no_remapping_devices(). That explanation confused me even more. So I've rechecked with intel_iommu=igfx_off and already thought I've made a decent fool of myself because I couldn't readily hang it. Turns out it's just much harder to hang with that. So I think moving around the tlb flushing for other dmar nodes to align with the idled igfx isn't a great solution, simply because I can't reliably tell whether it fixes anything. -Daniel -- Daniel Vetter Mail: daniel@ffwll.ch Mobile: +41 (0)79 365 57 48