From: "Mark Brown" <broonie@kernel.org>
Sent: Thursday, 16 May, 2024 14:13:19

On Wed, May 15, 2024 at 03:54:09PM +0200, Elinor Montmasson wrote:

quoted

Add an optional DT clock "cpu_sysclk" to get the CPU DAI system-clock
frequency when using the generic codec.
It is set for both Tx and Rx.
The way the frequency value is used is up to the CPU DAI driver
implementation.

quoted

+		struct clk *cpu_sysclk = clk_get(&pdev->dev, "cpu_sysclk");
+		if (!IS_ERR(cpu_sysclk)) {
+			priv->cpu_priv.sysclk_freq[TX] = clk_get_rate(cpu_sysclk);
+			priv->cpu_priv.sysclk_freq[RX] = priv->cpu_priv.sysclk_freq[TX];
+			clk_put(cpu_sysclk);
+		}

I don't really understand the goal here - this is just reading whatever
frequency happens to be set in the hardware when the driver starts up
which if nothing else seems rather fragile?

The driver allow to set the sysclk frequency
of the CPU DAI through `priv->cpu_priv.sysclk_freq` when calling
`fsl_asoc_card_hw_params()`.
Currently it is hard-coded per use-case in the driver.

My reasoning was that with a generic codec/compatible, there might
be use-cases needing to use this parameter, so I exposed it here via DT.

Is it a bad idea to expose this parameter ? This is not a requirement for the
driver to work, most of the current compatibles do not use this parameter.
It is currently used only for `fsl,imx-audio-cs42888`.
In that case I can remove this commit.

Best regards,
Elinor Montmasson