From mboxrd@z Thu Jan 1 00:00:00 1970 From: Larry Finger Subject: Re: Regression in i915 in kernel 4.6.0-git - bisected to f21a21983ef13a031 Date: Fri, 27 May 2016 10:17:53 -0500 Message-ID: <57486521.5030900@lwfinger.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Shubhangi Shrivastava , Jani Nikula , Daniel Vetter Cc: intel-gfx@lists.freedesktop.org, DRI , LKML List-Id: intel-gfx@lists.freedesktop.org The latest mainline kernel (commit 3f59de0) shows a regression. The symptom is that as soon as the kernel is started, the display is blanked, and it is never turned on again. This problem was bisected to commit f21a21983ef13a031250c4c3f6018e29a549d0f1 ("drm/i915: Splitting intel_dp_detect"). The adapter in question is the integrated graphics controller on a Toshiba Tecra A50 laptop. The output of "lspci -nnv" for that controller is as follows: 00:02.0 VGA compatible controller [0300]: Intel Corporation 4th Gen Core Processor Integrated Graphics Controller [8086:0416] (rev 06) (prog-if 00 [VGA controller]) Subsystem: Toshiba America Info Systems Device [1179:0002] Flags: bus master, fast devsel, latency 0, IRQ 27 Memory at e0000000 (64-bit, non-prefetchable) [size=4M] Memory at d0000000 (64-bit, prefetchable) [size=256M] I/O ports at 4000 [size=64] Expansion ROM at [disabled] Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit- Capabilities: [d0] Power Management version 2 Capabilities: [a4] PCI Advanced Features Kernel driver in use: i915 Kernel modules: i915 New information: I have used SSH to connect to the laptop to see the logs. In the dmesg output, I see "i915 0000:00:02.0: No connectors reported connected with modes". I will try to determine why that is happening. Larry