diff options
| author | Takashi Iwai <tiwai@suse.de> | 2016-03-19 10:40:21 +0100 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2016-03-20 08:38:32 +0100 |
| commit | 7169701ad3f9fadd7413b354ae317e67c0b37389 (patch) | |
| tree | 695a13b39276fbebd20afa65858e9ad18d4cc93b | |
| parent | 93a9ff151754fbdf951b1b993bcf96453f6e36b3 (diff) | |
ALSA: hda - Workaround for unbalanced i915 power refcount by concurrent probe
The recent addition of on-demand i915 audio component binding in the
codec driver seems leading to the unbalanced i915 power refcount,
according to Intel CI tests. Typically, it gets a kernel WARNING
like:
WARNING: CPU: 3 PID: 173 at sound/hda/hdac_i915.c:91 snd_hdac_display_power+0xf1/0x110 [snd_hda_core]()
Call Trace:
[<ffffffff813fef15>] dump_stack+0x67/0x92
[<ffffffff81078a21>] warn_slowpath_common+0x81/0xc0
[<ffffffff81078b15>] warn_slowpath_null+0x15/0x20
[<ffffffffa00f77e1>] snd_hdac_display_power+0xf1/0x110 [snd_hda_core]
[<ffffffffa015039d>] azx_intel_link_power+0xd/0x10 [snd_hda_intel]
[<ffffffffa011e32a>] azx_link_power+0x1a/0x30 [snd_hda_codec]
[<ffffffffa00f21f9>] snd_hdac_link_power+0x29/0x40 [snd_hda_core]
[<ffffffffa01192a6>] hda_codec_runtime_suspend+0x76/0xa0 [snd_hda_codec]
.....
The scenario is like below:
- HD-audio driver and i915 driver are probed concurrently at the
(almost) same time; HDA bus tries to bind with i915, but it fails
because i915 initialization is still being processed.
- Later on, HD-audio probes the HDMI codec, where it again tries to
bind with i915. At this time, it succeeds.
- At finishing the probe of HDA, it decreases the refcount as if it
were already bound at the bus probe, since the component is bound
now. This triggers a kernel WARNING due to the unbalance.
As a workaround, in this patch, we just disable the on-demand i915
component binding in the codec driver. This essentially reverts back
to the state of 4.4 kernel.
We know that this is no real solution, but it's a minimalistic simple
change that can be applied to 4.5.x kernel as stable.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94566
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: <stable@vger.kernel.org> # v4.5
Signed-off-by: Takashi Iwai <tiwai@suse.de>
| -rw-r--r-- | sound/pci/hda/patch_hdmi.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c index 56d3575ee6cc..7ae614d27954 100644 --- a/sound/pci/hda/patch_hdmi.c +++ b/sound/pci/hda/patch_hdmi.c @@ -2258,9 +2258,15 @@ static int patch_generic_hdmi(struct hda_codec *codec) /* Try to bind with i915 for Intel HSW+ codecs (if not done yet) */ if ((codec->core.vendor_id >> 16) == 0x8086 && is_haswell_plus(codec)) { +#if 0 + /* on-demand binding leads to an unbalanced refcount when + * both i915 and hda drivers are probed concurrently; + * disabled temporarily for now + */ if (!codec->bus->core.audio_component) if (!snd_hdac_i915_init(&codec->bus->core)) spec->i915_bound = true; +#endif /* use i915 audio component notifier for hotplug */ if (codec->bus->core.audio_component) spec->use_acomp_notifier = true; |