[PATCH 1/2] ASoC: fsl: fsl_ssi: add ac97 fixed mode support

[Primoz Fiser]

Hi Mark,

On 5. 10. 20 13:49, Mark Brown wrote:
> On Mon, Oct 05, 2020 at 01:16:43PM +0200, Primoz Fiser wrote:
> 
>> bits. But in summary, when SSI operates in AC'97 variable mode of
>> operation, CODECs can sometimes send SLOTREQ bits for non-existent audio
>> slots which then "stick" in SSI and completely break audio output.
> 
> If this is something that happens based on the CODEC shouldn't we be
> doing this by quirking based on the CODEC the system has rather than
> requiring people set a separate DT property?
> 

To be totally honest, we are not 100% sure if this is only CODEC's fault 
or something else might be causing these issues.

For example, it could be some EMI/noise that causes SLOTREQ bits to flip 
spuriously. Or it could even be the buggy SSI itself (taking into 
account all the issues with channel slipping, slot filtering, AC'97 reg 
reading/writing, etc)?

We are just referencing commit 01ca485171e3 ("ASoC: fsl_ssi: only enable 
proper channel slots in AC'97 mode"), as we saw that UDOO board had the 
same problems. I added commit author to CC.

We were able to overcome those by programming SSI in AC'97 fixed mode 
which driver up to now completely ignored (it was using only AC'97 
variable mode).

Additionally, we are using WM9712 codec and UDOO board is using VT1613, 
right? So these issues might not be CODEC related at all.

BR,
Primoz