[PATCH] cpufreq: scmi: Fix OPP addition failure with a dummy clock provider

[Viresh Kumar]

On 10-11-20, 11:10, Sudeep Holla wrote:
> Commit dd461cd9183f ("opp: Allow dev_pm_opp_get_opp_table() to return
> -EPROBE_DEFER") handles -EPROBE_DEFER for the clock/interconnects within
> _allocate_opp_table() which is called from dev_pm_opp_add and it
> now propagates the error back to the caller.
> 
> SCMI performance domain re-used clock bindings to keep it simple. However
> with the above mentioned change, if clock property is present in a device
> node, opps fails to get added with below errors until clk_get succeeds.
> 
>  cpu0: failed to add opp 450000000Hz
>  cpu0: failed to add opps to the device
>  ....(errors on cpu1-cpu4)
>  cpu5: failed to add opp 450000000Hz
>  cpu5: failed to add opps to the device
> 
> So, in order to fix the issue, we need to register dummy clock provider.
> With the dummy clock provider, clk_get returns NULL(no errors!), then opp
> core proceeds to add OPPs for the CPUs.
> 
> Cc: Rafael J. Wysocki <rjw at rjwysocki.net>
> Cc: Viresh Kumar <viresh.kumar at linaro.org>
> Fixes: dd461cd9183f ("opp: Allow dev_pm_opp_get_opp_table() to return -EPROBE_DEFER")
> Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
> ---
>  drivers/cpufreq/scmi-cpufreq.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
> index e855e8612a67..78318508a6d6 100644
> --- a/drivers/cpufreq/scmi-cpufreq.c
> +++ b/drivers/cpufreq/scmi-cpufreq.c
> @@ -8,6 +8,7 @@
>  
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>  
> +#include <linux/clk-provider.h>
>  #include <linux/cpu.h>
>  #include <linux/cpufreq.h>
>  #include <linux/cpumask.h>
> @@ -228,12 +229,17 @@ static struct cpufreq_driver scmi_cpufreq_driver = {
>  static int scmi_cpufreq_probe(struct scmi_device *sdev)
>  {
>  	int ret;
> +	struct device *dev = &sdev->dev;
>  
>  	handle = sdev->handle;
>  
>  	if (!handle || !handle->perf_ops)
>  		return -ENODEV;
>  
> +	/* dummy clock provider as needed by OPP if clocks property is used */
> +	if (of_find_property(dev->of_node, "#clock-cells", NULL))
> +		devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
> +
>  	ret = cpufreq_register_driver(&scmi_cpufreq_driver);
>  	if (ret) {
>  		dev_err(&sdev->dev, "%s: registering cpufreq failed, err: %d\n",

For 5.10-rc.

Acked-by: Viresh Kumar <viresh.kumar at linaro.org>

-- 
viresh