[MinnowBoard] Where is the MBM I2S driver in Linux

[Liam Girdwood]

On Tue, 2015-06-02 at 18:27 +0100, Strasser, Kevin wrote:
> Hi Li,
> 
> On 06/01/15 8:03 PM, li yuqian wrote:
> > check those driver, and i can understand there are three parts for the LPE
> > driver to working, special for the LPE firmware need to adde it. i can figure
> > it out in the
> > https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/tree/sound/soc/intel/sst-acpi.c?id=refs/tags/v4.0.4
> > line 249 and 250.
> >
> > but when i checked that sst-acpi.c, i found the baytrial sst is not support
> > the DMA data transfer, see the resindex_dma_base = -1 in line 262 and line 51
> > /* DMA only valid when resindex_dma_base != -1*/
> >
> > Am i correct? the MBM i2s does not support DMA data transfer?
> 
> You are correct, the Bay Trail LPE driver does not use DMA. I think that is just
> a driver limitation, and does not necessarily indicate that the hardware isn't
> capable.
> 
> Liam, can you provide any context here?

The BYT audio DSP driver does not use DMA for loading the FW from host
memory to DSP memory, but it does use DMA for audio playback and capture
(controlled by the FW). The BYT audio driver just does a memcpy() of the
FW from host to DSP memory.

Liam

> 
> Thanks,
> Kevin