[MinnowBoard] I2S Audio on MinnowBoard MAX Windows

[David Anders]

Ryan,


> On November 20, 2014 at 7:37 AM "Roberts, Ryan" <Ryan.Roberts at cirrus.com>
> wrote:
> 
> 
> Hi there,
> 
> First of all, appologies if this is not the correct place for Minnowboard MAX
> **Windows** questions, I could only find this elinux mailing list. Please
> direct me to the Windows list if it exists.
> 

this list is for anything max related that the community can support. you are
welcome to ask questions related to Microsoft Windows on MinnowMax, however, the
vast majority of community users are using linux or other open source operating
systems,

> I'm currently evaluating the suitability of MinnowBoard MAX as a platform that
> I could use for development and testing of Windows audio codec drivers. I have
> previous familiarity with the Baytrail LPE audio architecture and have a
> driver that works on other Baytrail based systems.
> 
> I've been able to successfully modify the ACPI DSDT to expose my codec device
> and the correct LPE device (there are two LPE devices in the DSDT - one for
> Android and the other for Windows. The BIOS seems to think it is booting to
> Android so some changes are required). I've also successfully installed the
> Intel LPE driver and Windows is happy that there are render and capture
> endpoints available (playback is shown as working)...
> 
> However, I have 2 problems:
> 
> 
> *         The LPE driver that I have is using I2S port 1 (the pins of which
> are multiplexed with HAD and are not brought out to headers). The MinnowBoard
> MAX schematic shows that I2S port 2 is the one that is brought out to the
> board's header. Is there an alternative LPE driver available that will use
> this port instead? If so, can you advise on where I can get it? (I took the
> driver that I'm currently using from Baytrail-T type 4).
> 
> 
> 
> *         The board does not bring out any of the PMC_PLT clocks out to the
> header. Previously the audio codec has always used PMC_PLT_CLK[3] on Baytrail
> running at 25MHz as its master clock. How/where do you envisage that we should
> get MCLK when using MinnowBoard MAX? Are there any options other than
> providing an external clock and attempting to synchronize to the I2S bit clock
> when it is active?
> 

there is a current known hardware issue on this. during development of the max
we had mistaken the capabilities of the ILB_8450_SPKR single as being able to be
used for the reference clock. only after production did we find out this was not
the case. 

https://bugzilla.yoctoproject.org/show_bug.cgi?id=6865

the next hardware revision of the Max will replace the ILB_8450_SPKR with one of
the PMC_PLT_CLK signals.

Dave


> Thanks in advance,
> Ryan Roberts
> 
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