Messages in this thread | | | Subject | Re: [PATCH 1/8] soundwire: intel: filter SoundWire controller device search | From | Pierre-Louis Bossart <> | Date | Wed, 8 May 2019 11:20:10 -0500 |
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>>>> + /* >>>> + * On some Intel platforms, multiple children of the HDAS >>>> + * device can be found, but only one of them is the SoundWire >>>> + * controller. The SNDW device is always exposed with >>>> + * Name(_ADR, 0x40000000) so filter accordingly >>>> + */ >>>> + if (adr != 0x40000000) >>> >>> I do not recall if 4 corresponds to the links you have or soundwire >>> device type, is this number documented somewhere is HDA specs? >> >> I thought it was a magic number, but I did check and for once it's >> documented and the values match the spec :-) >> I see in the ACPI docs bits 31..28 set to 4 indicate a SoundWire Link Type >> and bits 3..0 indicate the SoundWire controller instance, the rest is >> reserved to zero. > > So in that case we should mask with bits 31..28 and match, who knows you > may have multiple controller instances in future
yes, I was planning on only using the link type.
> I had a vague recollection that this was documented in the spec, glad > that in turned out to be the case. > > Btw was the update to HDA spec made public?
Not that I know of. The previous NHLT public doc has actually disappeared from the Intel site and I can't find it any longer, so currently the amount of public documentation is trending to zero :-(
> >>> Also it might good to create a define for this >> >> I will respin this one to add the documentation above, and only filter on >> the 4 ms-bits. Thanks for forcing me to RTFM :-) >
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