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SSP: need to support MCLK/BCLK/LRCLK on-demand on/off capabilities #629
Description
Some codecs need the MCLK/BCLK/LRCLK to be on before streaming starts (typically 10s of ms to avoid clicks/pops), see e.g. https://elixir.bootlin.com/linux/latest/source/sound/soc/intel/boards/kbl_rt5663_max98927.c#L86 for RT5663
The SSP IPC supports keeping the clock on a boot via the clks_control field, but it's not currently implemented. We would also miss IPC support for on/off requests on-demand (new IPC required?)
Adding @lgirdwood and @mmaka1 as assignees mainly to get comments on what IPC changes would be needed, the implementation can be done later.
Activity
lgirdwood commentedon Nov 28, 2018
This could be done with another optional IPC sent during prepare() and before trigger.
dbaluta commentedon Feb 22, 2019
@plbossart @lgirdwood
So the clocks handling is done on the host side and DSP sends requests for various operations on the clocks, right?
plbossart commentedon Feb 22, 2019
dbaluta commentedon Feb 22, 2019
@plbossart Thanks, I understand! On i.MX clock handling would be really fun to implement :). That's because the clock handling is taken care by a separate firmware (running on an M4) and now is handled with commands from the host (Linux) side. So for this reason I've asked about the direction.
lgirdwood commentedon Feb 25, 2019
@dbaluta looks like your i.MX SOF driver will need to program M4 ? There are PCM callbacks in the SOF HW abstraction layer so you could add your M4 programming to the hw_params() or prepare() callback ? Btw, if you need other callbacks, then feel free to send a PR.
mengdonglin commentedon Feb 22, 2022
Comments from Pierre "These features will be enabled with IPC4, in fact I am working on them at the moment since the way to control them is via a gateway configuration in addition to the binary blobs coming from NHLT.
The activation of clocks is handled with a 'gateway configuration', which is made of the 'SSP blob' along with additional commands to configure clocks early.
This capability is handled by the cAVS firmware... I am thinking this is part of the plan for the converged firmware."
@mwasko @lgirdwood Can you please confirm this capability will be supported by the converged firmware?
lgirdwood commentedon Feb 22, 2022
@mmaka1 @marcinszkudlinski pls confirm ?
mwasko commentedon Feb 28, 2022
yes
kv2019i commentedon Jan 3, 2025
Lowering to P2. FYI @lgirdwood @abonislawski