Re: [PATCH v2 2/3] soc: qcom: ice: Enable PM runtime for ICE driver

[Krzysztof Kozlowski]

On 12/05/2026 05:37, Linlin Zhang wrote:
> The QCOM ICE driver manages the ICE core clock through direct calls to
> clk_prepare_enable() and clk_disable_unprepare(), which limits integration

No, it does not limit any integration.

> with platforms that rely on firmware-managed resources or platform-specific
> power management mechanisms.

Nope. It's perfectly correct way of managing clocks. Adding runtime PM
ONLY to toggle clocks is absolute killer, pointless overhead without
benefits.

> 
> Replace direct clock management with runtime PM support by moving clock
> enable and disable into runtime PM callbacks. Use
> pm_runtime_resume_and_get() and pm_runtime_put_sync() in qcom_ice_resume()
> and qcom_ice_suspend() to drive power state transitions, and enable runtime
> PM in qcom_ice_probe().
> 
> Reviewed-by: Neeraj Soni <neeraj.soni@xxxxxxxxxxxxxxxx>
> Reviewed-by: Deepti Jaggi <deepti.jaggi@xxxxxxxxxxxxxxxx>
> Signed-off-by: Linlin Zhang <linlin.zhang@xxxxxxxxxxxxxxxx>
> ---
>  drivers/soc/qcom/ice.c | 58 ++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 53 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/soc/qcom/ice.c b/drivers/soc/qcom/ice.c
> index b203bc685cad..6f9d679b530c 100644
> --- a/drivers/soc/qcom/ice.c
> +++ b/drivers/soc/qcom/ice.c
> @@ -16,6 +16,7 @@
>  #include <linux/of.h>
>  #include <linux/of_platform.h>
>  #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
>  
>  #include <linux/firmware/qcom/qcom_scm.h>
>  
> @@ -310,8 +311,8 @@ int qcom_ice_resume(struct qcom_ice *ice)
>  	struct device *dev = ice->dev;
>  	int err;
>  
> -	err = clk_prepare_enable(ice->core_clk);
> -	if (err) {
> +	err = pm_runtime_resume_and_get(dev);
> +	if (err < 0) {
>  		dev_err(dev, "failed to enable core clock (%d)\n",
>  			err);
>  		return err;
> @@ -323,7 +324,7 @@ EXPORT_SYMBOL_GPL(qcom_ice_resume);
>  
>  int qcom_ice_suspend(struct qcom_ice *ice)
>  {
> -	clk_disable_unprepare(ice->core_clk);
> +	pm_runtime_put_sync(ice->dev);
>  	ice->hwkm_init_complete = false;
>  
>  	return 0;


This is pretty pointless change. At least by quick glance. You changed
nothing here for PM, except adding indirection layer and more locks.
Clocks will be gated the same way, no energy savings. But on the other
hand introducing runtime PM subsystem is huge bunch of code with its own
locks, completely unnecessary here.

This itself is poor choice and has NEGATIVE impact on all existing
platforms without any benefit.

I am surprised you went through SIX internal reviews, collected two
internal review tags and no one suggested that using runtime PM ONLY to
toggle clocks is pretty pointless and undesired.

Best regards,
Krzysztof