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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - [BAT SKL]igt@kms_pipe_crc_basic@suspend-read-crc-pipe-c fails suspend autoresume"
href="https://bugs.freedesktop.org/show_bug.cgi?id=94566#c28">Comment # 28</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - [BAT SKL]igt@kms_pipe_crc_basic@suspend-read-crc-pipe-c fails suspend autoresume"
href="https://bugs.freedesktop.org/show_bug.cgi?id=94566">bug 94566</a>
from <span class="vcard"><a class="email" href="mailto:imre.deak@intel.com" title="Imre Deak <imre.deak@intel.com>"> <span class="fn">Imre Deak</span></a>
</span></b>
<pre>(In reply to Takashi Iwai from <a href="show_bug.cgi?id=94566#c26">comment #26</a>)
<span class="quote">>[...]
> > >
> > > Yes, but it shouldn't fail for the Realtek audio codec, but should fail
> > > (drop) only HDMI codec.
> >
> > Assuming the limitation that the HDMI codec cannot be registered
> > dynamically, the Realtek codec probing should also fail in this case. Yes,
> > it sucks, but that's inherent in the audio framework and not a problem of
> > the HDA driver.
>
> Sorry, this no-go. </span >
To support this you need to fix the audio framework to allow for dynamic
registration of the HDMI codec.
<span class="quote">> It's a clear regression from the previous kernels, and I
> know people expecting this works like that. (I've got bug reports in the
> past for similar things already.)</span >
Could you describe the exact configuration? Is Intel HDMI support enabled in
Kconfig? Is there an Intel HDMI codec present in the bug reporter's system?
<span class="quote">> > In any case this can only arise due to a kernel
> > configuration problem, or in case of an error as discussed earlier, so in
> > both cases it's not too unexpected to lose audio.
>
> It's not always an "error".</span >
Please specify in which case, I would like to better understand.
<span class="quote">> nomodeset option, for example, should be possible to be handled gracefully.</span >
You can check if nomodeset was passed on the command line.
<span class="quote">> The missing i915 module can be seen as a configuration error, and we have
> some excuse not to make things working well. But nomodeset is just a
> runtime configuration, and it shouldn't affect the things that worked in
> previous kernels.
>
> > > Here comes back to the question again: for knowing what codec is on the bus,
> > > we already need i915 binding.
> >
> > To know that there is an Intel HDMI codec on the bus, you don't need the
> > binding you can just look at PCIIDs.
>
> No, on SKL or BSW, there is no PCI controller for HDMI.</span >
So why not check for the presence of SKL, BSW etc. graphics PCIIDs? That does
indicate the presence of an HDMI codec.
<span class="quote">> > At this point you know you'll have to
> > delay the probing of the HDMI codec (or any other codec due to the audio
> > framework limitation) until the component binding completes.
> >
> > > But how to fail i915 binding in this case?
> >
> > You don't need to fail it, whenever the audio driver decides to wait for the
> > binding to complete (based on PCIIDs and Intel HDMI support being enabled in
> > the audio Kconfig) the i915 driver must be present (because of a Kconfig
> > dependency) and loaded eventually. The only cases when binding wouldn't
> > complete are exceptional, the nomodeset and error cases discussed earlier.
>
> The question is how to decide to wait or not.
> For nomodeset case, clearly we shouldn't wait.</span >
The audio driver can check if nomodeset was passed.
<span class="quote">> > > Will i915 driver inform to component?
> >
> > In which case? The only reason i915 wouldn't initiate the binding is some
> > error case, when it's also ok to fail audio probing (provided the audio
> > driver decided to wait based on the previous point).
>
> Well, my question is how the audio driver knows that i915 failed to register
> the slave. Otherwise the audio driver will wait forever with a hope i915
> will register anytime later.
>
> > > What if the module isn't present (e.g. in the limited initrd)?
> >
> > And it's in the rootfs only? Then it's ok to wait with audio probing until
> > the i915 module gets loaded from the rootfs.
>
> The question is how long we may block. I guess some blocking behavior with
> timeout is acceptable for this particular case, as it's a system
> configuration problem. But again, nomodeset is a different matter.</span >
I don't think we need some timeout, it's an exceptional case if binding doesn't
complete in a timely manner.</pre>
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