Bug 1196586

Summary: 'Warning: at drivers/gpu/drm/i915/intel_display.c:6015 hsw_disable_lcpll+0x514/0x640 [i915]' message appears in kernel logs when system boots with no display attached
Product: Red Hat Enterprise Linux 7 Reporter: Siteshwar Vashisht <svashisht>
Component: kernelAssignee: Rob Clark <rclark>
kernel sub component: Graphics QA Contact: Desktop QE <desktop-qa-list>
Status: CLOSED CURRENTRELEASE Docs Contact:
Severity: medium    
Priority: medium CC: ajb, hvyas, phil, svashisht, toracat, tpelka
Version: 7.0   
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2015-04-16 17:31:23 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1205791    

Description Siteshwar Vashisht 2015-02-26 10:38:17 UTC 
Description of problem:

Below warning appears in kernel logs when system boots with no display attached :

[   62.783032] WARNING: at drivers/gpu/drm/i915/intel_display.c:6015 hsw_disable_lcpll+0x514/0x640 [i915]()
[   62.783034] Power well on
[   62.783035] Modules linked in: ipt_MASQUERADE xt_CHECKSUM sg nfsv3 rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache ip6t_rpfilter ip6t_REJECT ipt_REJECT xt_conntrack ebtable_nat ebtable_broute bri
dge stp llc ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw ip6table_filter ip6_tables iptable_nat nf_conntrack_ipv4
 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw iptable_filter ip_tables iTCO_wdt iTCO_vendor_support snd_hda_codec_idt snd_hda_codec_generic snd_hda_cod
ec_hdmi snd_hda_intel snd_hda_codec snd_hwdep snd_seq snd_seq_device coretemp snd_pcm usb_storage kvm_intel lpc_ich kvm crct10dif_pclmul crc32_pclmul crc32c_intel mfd_core ghash_clmulni_intel crypt
d serio_raw pcspkr snd_page_alloc
[   62.783060]  i2c_i801 snd_timer snd acpi_cpufreq shpchp mperf soundcore mei_me mei nfsd auth_rpcgss nfs_acl lockd sunrpc uinput xfs libcrc32c sd_mod crc_t10dif crct10dif_common ahci libahci liba
ta igb i915 e1000e dca ptp pps_core i2c_algo_bit drm_kms_helper aacraid drm video i2c_core dm_mirror dm_region_hash dm_log dm_mod
[   62.783076] CPU: 0 PID: 513 Comm: kworker/0:2 Tainted: G        W   --------------   3.10.0-123.20.1.el7.x86_64 #1
[   62.783078] Hardware name: SIEMENS AG SIMATIC IPC647D/A5E34747514, BIOS V19.01.04 12/08/2014
[   62.783090] Workqueue: events hsw_enable_pc8_work [i915]
[   62.783091]  ffff88003687bd60 00000000fa17222f ffff88003687bd18 ffffffff815e2b0c
[   62.783093]  ffff88003687bd50 ffffffff8105dee1 ffff880036bcc000 ffff88022f077448
[   62.783095]  0000000000000001 0000000000000001 ffff88022f077450 ffff88003687bdb8
[   62.783098] Call Trace:
[   62.783102]  [<ffffffff815e2b0c>] dump_stack+0x19/0x1b
[   62.783106]  [<ffffffff8105dee1>] warn_slowpath_common+0x61/0x80
[   62.783109]  [<ffffffff8105df5c>] warn_slowpath_fmt+0x5c/0x80
[   62.783123]  [<ffffffffa0164e84>] hsw_disable_lcpll+0x514/0x640 [i915]
[   62.783137]  [<ffffffffa0165561>] hsw_enable_pc8_work+0x81/0xc0 [i915]
[   62.783141]  [<ffffffff8107e03b>] process_one_work+0x17b/0x460
[   62.783143]  [<ffffffff8107ee0b>] worker_thread+0x11b/0x400
[   62.783146]  [<ffffffff8107ecf0>] ? rescuer_thread+0x400/0x400
[   62.783148]  [<ffffffff81085aff>] kthread+0xcf/0xe0
[   62.783151]  [<ffffffff81085a30>] ? kthread_create_on_node+0x140/0x140
[   62.783154]  [<ffffffff815f316c>] ret_from_fork+0x7c/0xb0
[   62.783156]  [<ffffffff81085a30>] ? kthread_create_on_node+0x140/0x140


Version-Release number of selected component (if applicable):
kernel-3.10.0-123.el7.x86_64

How reproducible:
The warning only occurs when no display is connected to the system

Steps to Reproduce:
Boot with no display attached to the system.

Additional info:

Earlier discussion http://lists.freedesktop.org/archives/intel-gfx/2013-December/037426.html and upstream patch  https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=be3d26b0588ca5f4db6b50d13e92afb0ac57d6ab
Comment 5 Rob Clark 2015-04-16 17:31:23 UTC 
I expect this to have been fixed in rhel71, and at least one reporter has confirmed so.  So I am closing this.