[MinnowBoard] SSP Ports and LPE DMA blocks

[Roberts, Ryan]

Apologies, I originally sent the below message to the wrong mailing list address. If anyone can point me to any relevant Linux code that would be great.

Begin forwarded message:

From: "Roberts, Ryan" <Ryan.Roberts at cirrus.com<mailto:Ryan.Roberts at cirrus.com>>
Date: 3 March 2015 19:04:39 GMT
To: "elinux-minnowboard-bounces at lists.elinux.org<mailto:elinux-minnowboard-bounces at lists.elinux.org>" <elinux-minnowboard-bounces at lists.elinux.org<mailto:elinux-minnowboard-bounces at lists.elinux.org>>
Subject: SSP Ports and LPE DMA blocks

Hi all,

I am currently trying to write a driver for Windows to drive the SSP port on the Minnow Board MAX (to send and receive I2S data). I’m using the LPE DMA block to transfer data between main memory and the SSP peripheral. However, I am getting an interrupt storm from the DMA controller after completing the first transfer; clearly I am not clearing the interrupt correctly.

The Intel documentation is pretty sparse so was wondering if any code exists on the Linux side to deal with this that we could use as an example? I’ve looked in the upstream kernel and don’t see anything (Standard Baytrail audio is transferred to the LPE then the LPE transfers it to the SSP, and the LPE sets up the DMA, and that code is a blob). Is there any MBM specific tree that I could look in?

Thanks,
Ryan


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