[keyonjie]

Add .pcm_pointer ops for cannonlake to read DPIB/posbuf and get pointer
for ALSA, to align with apollolake.

Signed-off-by: Keyon Jie yang.jie@linux.intel.com

[bardliao]

Thanke @keyonjie this PR fixes #812

[mengdonglin]

This PR also fixed #820. Thanks @keyonjie

[fredoh9]

@keyonjie
should ops->pcm_pointer be set for all platforms after SKL+?
cnl.c is the machine driver for cnl, cml, whl etc all for cAVS 1.8?

[wenqingfu]

cnl.c is the machine driver for cnl, cml, whl etc all for cAVS 1.8?

yes

[plbossart]

I will merge but that illustrates how flaky our handling of the hw_ptr is. If using DPIB for the position is required for a functional product, then what was this discussion about FORCE_DEBUG_IPC_POSITION all about?
We need to raise our game with devices that work by-design and not by accident, sometimes, depending on which information is used.

[ranj063]

cnl.c is the machine driver for cnl, cml, whl etc all for cAVS 1.8?

@fredoh9 not the machine driver but the audio device driver.

[xiulipan]

@plbossart
Actually we should be able to switch between IPC position update and DPIB position update.
BYT will always working on IPC position update, and WHL is accidentally set to run on IPC position update by default. We can use the force IPC update later on WHL.

The problem now is: BYT( with IPC position) is not stable and has a lot of issues in quality and IPC. We are not sure if they are related to IPC position update or DMA.
Related issues and PRs
#808 thesofproject/sof#1257 thesofproject/sof#1247

[plbossart]

Actually we should be able to switch between IPC position update and DPIB position update.

This PR shows the opposite, using IPC position update generates problems with PulseAudio.

[xiulipan]

@plbossart
Yes, that is the problem here. We have not test with PulseAudio for long time. But we still have BYT can only work with IPC position update. So maybe PulseAudio with BYT will also have problem。

@stevyan @Jiangxinx
Could you help to check if there is similar issues on BYT with PulseAudio enabled.