Re: [PATCH] clk: samsung: exynos5-subcmu: Defer probe until power domains are available

[Henrik Grimler <henrik@grimler.se>]

Hi Marek,

On Tue, Oct 13, 2026 at 01:18:38PM +0200, Marek Szyprowski wrote:
> Sub-CMU devices are added to their power domains with
> of_genpd_add_device() during exynos5_clk_probe(). Its return value is
> ignored, so if the power domain provider is not registered yet, the
> sub-CMU device is silently left outside of its power domain.
> 
> Since commit c09a3e6c97f0 ("soc: samsung: pm_domains: Convert to regular
> platform driver"), power domain providers are registered only when their
> platform devices are probed, which happens after exynos5_clk_probe() has
> already been called.
> 
> When a sub-CMU device is outside of its power domain, its runtime PM
> callbacks race with the power domain state changes, which might result in
> losing the proper hardware state. In practice, some clock muxes are left
> switched to the oscillator instead of the respective PLLs.
> 
> Fix this by deferring exynos5_clk_probe() until the platform devices for
> all available power domains are instantiated.
> 
> Fixes: c09a3e6c97f0 ("soc: samsung: pm_domains: Convert to regular platform driver")
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

Reviewed-by: Henrik Grimler <henrik@grimler.se>

I have noticed the same issue on my boards, and the fix looks good to
me. Thanks for fixing it!

Best regards,
Henrik Grimler

> ---
>  drivers/clk/samsung/clk-exynos5-subcmu.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/samsung/clk-exynos5-subcmu.c b/drivers/clk/samsung/clk-exynos5-subcmu.c
> index 373129847301..587fe6e3bbed 100644
> --- a/drivers/clk/samsung/clk-exynos5-subcmu.c
> +++ b/drivers/clk/samsung/clk-exynos5-subcmu.c
> @@ -6,6 +6,7 @@
>  
>  #include <linux/io.h>
>  #include <linux/of.h>
> +#include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_domain.h>
>  #include <linux/pm_runtime.h>
> @@ -155,11 +156,25 @@ static int __init exynos5_clk_register_subcmu(struct device *parent,
>  
>  static int __init exynos5_clk_probe(struct platform_device *pdev)
>  {
> +	static const char pd_node_name[] = "samsung,exynos4210-pd";
>  	struct device_node *np;
>  	const char *name;
>  	int i;
>  
> -	for_each_compatible_node(np, NULL, "samsung,exynos4210-pd") {
> +	/* Defer until all needed power domains are registered */
> +	for_each_compatible_node(np, NULL, pd_node_name) {
> +		if (of_device_is_available(np)) {
> +			struct platform_device *pd = of_find_device_by_node(np);
> +
> +			if (!pd) {
> +				of_node_put(np);
> +				return -EPROBE_DEFER;
> +			}
> +			put_device(&pd->dev);
> +		}
> +	}
> +
> +	for_each_compatible_node(np, NULL, pd_node_name) {
>  		if (of_property_read_string(np, "label", &name) < 0)
>  			continue;
>  		for (i = 0; i < nr_cmus; i++)
> -- 
> 2.43.0
> 
>