From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?utf-8?Q?Bj=C3=B8rn_Mork?= Subject: Regression in v4.5-rc1, bisected to commit 39bfcd5235e0 ("drm/i915: more virtual south bridge detection") Date: Mon, 25 Jan 2016 03:52:25 +0100 Message-ID: <87y4bes74m.fsf@nemi.mork.no> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Gerd Hoffmann Cc: Daniel Vetter , Jani Nikula , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org List-Id: intel-gfx@lists.freedesktop.org Hello, my oldish Thinkpad X301 only wanted to show a blank screen in v4.5-rc1. Bisecting resulted in: HEAD is now at 39bfcd5235e0 drm/i915: more virtual south bridge detecti= on 39bfcd5235e07e95ad3e70eab8e0b85db181de9e is the first bad commit commit 39bfcd5235e07e95ad3e70eab8e0b85db181de9e Author: Gerd Hoffmann Date: Thu Nov 26 12:03:51 2015 +0100 drm/i915: more virtual south bridge detection =20 Commit "30c964a drm/i915: Detect virtual south bridge" detects and handles the southbridge emulated by vmware esx. Add the ich9 south bridge emulated by 'qemu -M q35'. =20 Signed-off-by: Gerd Hoffmann Signed-off-by: Daniel Vetter :040000 040000 b59ceb519d517a00e41e575346505b9ebde06288 825eb4e5684952d= e0931312183d1cf163c43219a M drivers I have confirmed tha reverting this commit on top of v4.5-rc1 fixes the problem. And looking into the details, I believe this makes sense. Th= e patch does this (where id is a 0xff00 masked device ID): diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i91= 5_drv.c index 649e20aaa3ff..90faa8e03fca 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -565,7 +565,8 @@ void intel_detect_pch(struct drm_device *dev) DRM_DEBUG_KMS("Found SunrisePoint LP PC= H\n"); WARN_ON(!IS_SKYLAKE(dev) && !IS_KABYLAKE(dev)); - } else if (id =3D=3D INTEL_PCH_P2X_DEVICE_ID_TY= PE) { + } else if ((id =3D=3D INTEL_PCH_P2X_DEVICE_ID_T= YPE) || + (id =3D=3D INTEL_PCH_QEMU_DEVICE_ID_= TYPE)) { dev_priv->pch_type =3D intel_virt_detec= t_pch(dev); } else continue; diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i91= 5_drv.h index 3d8741eff7d3..439226d39437 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -2609,6 +2609,7 @@ struct drm_i915_cmd_table { #define INTEL_PCH_SPT_DEVICE_ID_TYPE 0xA100 #define INTEL_PCH_SPT_LP_DEVICE_ID_TYPE 0x9D00 #define INTEL_PCH_P2X_DEVICE_ID_TYPE 0x7100 +#define INTEL_PCH_QEMU_DEVICE_ID_TYPE 0x2900 /* qemu q35 has = 2918 */ =20 #define INTEL_PCH_TYPE(dev) (__I915__(dev)->pch_type) #define HAS_PCH_SPT(dev) (INTEL_PCH_TYPE(dev) =3D=3D PCH_SPT) =46WIW, the very real ISA bridge of my laptop matches the above: bjorn@nemi:~$ lspci -vvvnns1f.0 00:1f.0 ISA bridge [0601]: Intel Corporation ICH9M-E LPC Interface Cont= roller [8086:2917] (rev 03) Subsystem: Lenovo ICH9M-E LPC Interface Controller [17aa:20f5] Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- Par= Err- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=3Dmedium >TAbo= rt- SERR- Kernel driver in use: lpc_ich Kernel modules: lpc_ich This is a GM45 chipset. I believe most chipsets of this generation use 29xx device IDs for the ISA bridge. For example the P35: bjorn@canardo:~$ lspci -nns1f.0 00:1f.0 ISA bridge [0601]: Intel Corporation 82801IB (ICH9) LPC Interf= ace Controller [8086:2918] (rev 02) You cannot assume all these are virtual systems. There are still crazy people out there using the real thing :) Bj=C3=B8rn