[PATCH v2 3/3] ASoC: sunxi: sun4i-spdif: Reorder clock enable sequence

[Bui Duc Phuc]

Hi Chen-yu,

Thanks for your feedback

On Sat, May 23, 2026 at 2:20 AM Chen-Yu Tsai <wens at kernel.org> wrote:
> > Enable the APB bus clock before the SPDIF module clock
> > during runtime resume, as register accesses depend on the
> > bus clock being enabled first.
>
> That does not even matter here. Access will only happen once the runtime
> PM callbacks return.
>

I understand your point that ⁠sun4i-spdif⁠ doesn't immediately access
registers within the current ⁠runtime_resume⁠ path, so the order might
not trigger a failure right now.

However, if we look at the peer driver for the same Sunxi SoC family,
⁠sun4i-i2s.c⁠:
Links:
https://elixir.bootlin.com/linux/v7.0-rc5/source/sound/soc/sunxi/sun4i-i2s.c#L1296
In ⁠sun4i_i2s_runtime_resume()⁠, the sequence is strictly enforced as:

1. Enable bus clock
2. Access and restore/sync I2S registers
3. Enable module clock

Since both IP blocks belong to the same Sunxi platform and share similar
bus/module clock relationships, shouldn't we maintain architectural
consistency across these drivers?

Enforcing the "bus clock before module clock" order keeps the dependency
ordering aligned with the actual hardware roles, where the bus clock is
required for register access while the module clock drives the functional
audio path.

Wouldn't keeping this order also make the runtime PM behavior more
consistent and easier to follow across the Sunxi audio drivers?

Best Regards,
Phuc