On Tue, 15 Mar 2016 18:22:56 +0100, Takashi Iwai wrote: > > On Tue, 15 Mar 2016 17:02:07 +0100, > Ville Syrjälä wrote: > > This other one was seen at least on on SKL: > > [ 124.808525] ------------[ cut here ]------------ > > [ 124.808545] WARNING: CPU: 3 PID: 173 at sound/hda/hdac_i915.c:91 snd_hdac_display_power+0xf1/0x110 [snd_hda_core]() > > This is a different one, and it implies that the unbalanced power > refcount. Might be related with the recent fix for the recursive > regmap deadlock. I'll try later with a SKL machine here, too. > > Didn't you see this before the recent tree, right? Some good/bad > commits would be really helpful... So, we got a full log in bugzilla, and this looks like the on-demand binding leading to the unbalanced refcount. Could you try the patch below? This essentially reverts to the 4.4 state, so a "regression" should be covered, at least. It's applied on top of sound.git tree for-linus branch. (But it should be easily applicable to older trees, too.) We need a proper fix later, but now more urgently the CI test regression has to be papered over. thanks, Takashi -- 8< -- From: Takashi Iwai <tiwai@xxxxxxx> Subject: [PATCH] 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@xxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # v4.5 Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> --- sound/pci/hda/patch_hdmi.c | 6 ++++++ 1 file changed, 6 insertions(+) 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; -- 2.7.4 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
