From: "Mark Brown" <broonie@kernel.org>
Sent: Thursday, 16 May, 2024 14:18:00

On Wed, May 15, 2024 at 03:54:10PM +0200, Elinor Montmasson wrote:

quoted

Add new optional DT property "cpu-system-clock-direction-out" to set
sysclk direction as "out" for the CPU DAI when using the generic codec.
It is set for both Tx and Rx.
If not set, the direction is "in".
The way the direction value is used is up to the CPU DAI driver
implementation.

This feels like we should be using the clock bindings to specify the
clock input of whatever is using the output from the SoC, though that's
a lot more work.

Similarly to patch 7/9, I exposed this parameter because the driver has it, and
because there might be CPU DAIs needing this parameter.
Otherwise the cpu sysclk direction will always be IN as a default.
This parameter could be needed for cases with CPU DAIs, such as an SAI,
which can provide or consume Tx/Rx clocks.
For these devices I know the sysclk direction should correspond to
what was set in the dai format.

This new compatible is intended to be used when there is no codec
device/driver. There is technically no codec device/driver for which
the clock input can be set.

Is it a bad idea to allow setting the cpu sysclk direction only ?
Should the compatible be limited to use-cases where the cpu sysclk
direction cannot be set by the machine driver ?

Best regards,
Elinor Montmasson