[alsa-devel] [Patch V4 03/10] ASoC: qcom: Document LPASS CPU bindings

[Mark Brown]

On Thu, Feb 05, 2015 at 12:53:39PM -0800, Kenneth Westfield wrote:

> +- qcom,system-clock-shift		: Add this bool property if the default
> +					  frequency of the system clock needs to
> +					  be reduced.
> +- qcom,system-clock-shift-compare	: A numerical value used to right-shift
> +					  the default system clock frequency for
> +					  comparison with the target bit clock
> +					  frequency.
> +- qcom,system-clock-shift-amount	: A numerical value used to right-shift
> +					  the default system clock frequency.
> +- qcom,alternate-sysclk			: Add this bool property if the default
> +					  frequency of the system clock cannot
> +					  divide down to the target bit clock
> +					  frequency.
> +- qcom,alternate-sysclk-bitwidth	: A numerical value representing the
> +					  sample bitwidth which requires use of
> +					  the alternate system clock frequency.
> +- qcom,alternate-sysclk-frequency	: A numerical value representing the new
> +					  system clock frequency to use.

None of these seem like they are appropriate for device tree properties,
they appear to be choosing a specific clocking configuration which is
something that would normally be done as part of the system integration
in the machine driver rather than in the DAI driver.  This binding won't
work in cases where the clocks are being changed at runtime and would
limit systems where that becomes possible in future.

Further, the interface seems too low level - it's specifying individual
dividers and so on which would normally be things that can trivially be
calculated or inferred given the input and target clock rates.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 473 bytes
Desc: Digital signature
URL: <http://mailman.alsa-project.org/pipermail/alsa-devel/attachments/20150207/d6939ad0/attachment.sig>