[Intel-gfx] HPD flood warning since b8f102e8b

[Jiri Kosina]

During resume from hibernation, I started to see the warning below since

	commit b8f102e8bf71cacf33326360fdf9dcfd1a63925b
	Author: Egbert Eich <eich at suse.de>
	Date:   Fri Jul 26 14:14:24 2013 +0200

	    drm/i915: Add messages useful for HPD storm detection debugging (v2)

the system is otherwise working properly, and so far it seems to happen 
only during hibernation resume.

  [13766.703229] WARNING: CPU: 1 PID: 0 at drivers/gpu/drm/i915/i915_irq.c:1001 i965_irq_handler+0x492/0x680 [i915]()
  [13766.703230] Received HPD interrupt although disabled
  [13766.703335] Modules linked in: af_packet tun iptable_mangle xt_DSCP nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables xt_tcpudp nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack iptable_filter ip_tables x_tables rfcomm bn
  ep btusb bluetooth cpufreq_conservative cpufreq_userspace cpufreq_powersave iTCO_wdt iTCO_vendor_support snd_hda_codec_conexant snd_hda_intel snd_hda_codec kvm_intel snd_hwdep kvm snd_pcm thinkpad_acpi snd_seq iwldvm mac80211 sg snd_timer 
  iwlwifi snd_seq_device cfg80211 snd i2c_i801 pcspkr rfkill lpc_ich mfd_core e1000e ehci_pci snd_page_alloc ptp pps_core tpm_tis tpm soundcore battery ac wmi tpm_bios acpi_cpufreq autofs4 uhci_hcd ehci_hcd usbcore usb_common i915 drm_kms_he
  lper drm i2c_algo_bit video button edd fan processor ata_generic thermal thermal_sys
  [13766.703339] CPU: 1 PID: 0 Comm: swapper/1 Tainted: G        W    3.12.0-rc3 #1
  [13766.703341] Hardware name: LENOVO 7470BN2/7470BN2, BIOS 6DET38WW (2.02 ) 12/19/2008
  [13766.703350]  00000000000003e9 ffff88007c283d18 ffffffff81583013 ffff88007c283d58
  [13766.703357]  ffffffff8104d297 ffff88007c283d98 000000000000000c 0000000000000002
  [13766.703365]  ffff880037158000 0000000000000004 ffff880037158000 ffff88007c283db8
  [13766.703367] Call Trace:
  [13766.703375]  <IRQ>  [<ffffffff81583013>] dump_stack+0x7a/0x97
  [13766.703382]  [<ffffffff8104d297>] warn_slowpath_common+0x87/0xb0
  [13766.703388]  [<ffffffff8104d361>] warn_slowpath_fmt+0x41/0x50
  [13766.703425]  [<ffffffffa00c7be2>] i965_irq_handler+0x492/0x680 [i915]
  [13766.703436]  [<ffffffff810a40fc>] handle_irq_event_percpu+0xac/0x220
  [13766.703442]  [<ffffffff810a42b9>] handle_irq_event+0x49/0x70
  [13766.703449]  [<ffffffff810a7b2f>] handle_edge_irq+0x7f/0x150
  [13766.703454]  [<ffffffff81004a89>] handle_irq+0x59/0x150
  [13766.703461]  [<ffffffff8158d371>] ? atomic_notifier_call_chain+0x11/0x20
  [13766.703466]  [<ffffffff8100403b>] do_IRQ+0x5b/0xe0
  [13766.703474]  [<ffffffff815895af>] common_interrupt+0x6f/0x6f
  [13766.703482]  <EOI>  [<ffffffff8146cf74>] ? cpuidle_enter_state+0x54/0xd0
  [13766.703488]  [<ffffffff8146cf70>] ? cpuidle_enter_state+0x50/0xd0
  [13766.703496]  [<ffffffff8146d37a>] cpuidle_idle_call+0x10a/0x160
  [13766.703503]  [<ffffffff8100b7b9>] arch_cpu_idle+0x9/0x30
  [13766.703509]  [<ffffffff810a35cb>] cpu_idle_loop+0x8b/0x270
  [13766.703515]  [<ffffffff810a37ce>] cpu_startup_entry+0x1e/0x20
  [13766.703522]  [<ffffffff8103115e>] start_secondary+0x8e/0x90
  

It's not a single occurence, it's quite a flood within the same second, 
ending with

  [drm] GMBUS [i915 gmbus dpb] timed out, falling back to bit banging on pin 5
  [drm] HPD interrupt storm detected on connector HDMI-A-1: switching from hotplug detection to pollin

If this really needs to be enabled unconditionally by default (?), having 
it to warn only once would be nice.

If there is anything else I could do to make this go away, please let me 
know. I don't want to be running Tainted: W kernel from now forever on :)

This is a standard x200s thinkpad, no fancy development HW.

-- 
Jiri Kosina
SUSE Labs