From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH] Revert "drm/i915: Calculate correct stolen size for GEN7+" Date: Tue, 7 May 2013 19:02:15 +0200 Message-ID: <20130507170215.GM5763@phenom.ffwll.local> References: <1367431234-8448-1-git-send-email-ben@bwidawsk.net> <20130501180310.GA8556@bwidawsk.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-ee0-f41.google.com (mail-ee0-f41.google.com [74.125.83.41]) by gabe.freedesktop.org (Postfix) with ESMTP id C19E6E6264 for ; Tue, 7 May 2013 09:59:08 -0700 (PDT) Received: by mail-ee0-f41.google.com with SMTP id c50so463409eek.28 for ; Tue, 07 May 2013 09:59:08 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20130501180310.GA8556@bwidawsk.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Ben Widawsky Cc: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Wed, May 01, 2013 at 11:03:10AM -0700, Ben Widawsky wrote: > On Wed, May 01, 2013 at 11:00:34AM -0700, Ben Widawsky wrote: > > This reverts commit 03752f5b7b77b95d83479885040950fba1250850. > > > > This revert requires a bit of explanation on how I understand things > > work. Internally the architects/designers decide how the stolen encoding > > works. We put it in a doc. BIOS writers take these docs and implement > > it. Driver writers read the doc too, and read the value left by the BIOS > > writers, and then we make magic. > > > > The failing here is that in the docs we had[1] contained two different > > definitions for this register for Gen7. (We have both a PCI register, > > and an MMIO, and each of these were different). At the time [2] of > > 03752f5, we asked the architects what the correct value should be; but > > that doesn't match the reality (BIOS) unfortunately. > > > > So on all machines I can get my hands on, this revert is the right thing > > to do. I've also worked with the product group to confirm that they > > agree this revert is what we should do. People using HW made my "people" > > who both write their own BIOS, and have access to our docs (Apple?) > > Ooops, left this bit out... These "people" may not agree with the > revert. I don't have machines to test. > > > > > [1] The docs are still wrong on this one. Now instead of two registers with > > two definitions, we have one register with BOTH definitions, progress? > > [2] The open source PRMs have the "wrong" definitions in chapter Volume > > 1 part6, section 1.1.12. > > > > This digging was inspired by Paulo. > > > > Conflicts: > > drivers/gpu/drm/i915/i915_gem_gtt.c > > > > Cc: Paulo Zanoni > > Signed-off-by: Ben Widawsky Picked up for -fixes, thanks for the patch. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch