Re: [PATCH] serial: sprd: Return -EPROBE_DEFER when uart clock is not ready

[Andy Shevchenko]

On Wed, Oct 22, 2025 at 11:08:40AM +0800, Wenhua Lin wrote:
> In sprd_clk_init(), when devm_clk_get() returns -EPROBE_DEFER
> for either uart or source clock, we should propagate the
> error instead of just warning and continuing with NULL clocks.
> 
> Currently the driver only emits a warning when clock acquisition
> fails and proceeds with NULL clock pointers. This can lead to
> issues later when the clocks are actually needed. More importantly,
> when the clock provider is not ready yet and returns -EPROBE_DEFER,
> we should return this error to allow deferred probing.
> 
> This change adds explicit checks for -EPROBE_DEFER after both:
> 1. devm_clk_get(uport->dev, uart)
> 2. devm_clk_get(uport->dev, source)
> 
> When -EPROBE_DEFER is encountered, the function now returns
> -EPROBE_DEFER to let the driver framework retry probing
> later when the clock dependencies are resolved.

...

>  	clk_uart = devm_clk_get(uport->dev, "uart");
>  	if (IS_ERR(clk_uart)) {
> +		if (PTR_ERR(clk_uart) == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
> +
>  		dev_warn(uport->dev, "uart%d can't get uart clock\n",
>  			 uport->line);
>  		clk_uart = NULL;

AFAICS this still ignores other issues, what should be done here is to
replace devm_clk_get() by devm_clk_get_optional() and drop this NULL
assignment.

...

>  	clk_parent = devm_clk_get(uport->dev, "source");
>  	if (IS_ERR(clk_parent)) {
> +		if (PTR_ERR(clk_parent) == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
> +
>  		dev_warn(uport->dev, "uart%d can't get source clock\n",
>  			 uport->line);
>  		clk_parent = NULL;

Ditto.

-- 
With Best Regards,
Andy Shevchenko