linux-kernel - Re: [Patch v5 4/6] soc: qcom: Extend RPMh power controller driver to register warming devices.

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Message-ID: <20200327225345.GH5063@builder>
Date:   Fri, 27 Mar 2020 15:53:45 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Thara Gopinath <thara.gopinath@...aro.org>
Cc:     rui.zhang@...el.com, ulf.hansson@...aro.org,
        daniel.lezcano@...aro.org, agross@...nel.org, robh@...nel.org,
        amit.kucheria@...durent.com, mark.rutland@....com,
        rjw@...ysocki.net, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Patch v5 4/6] soc: qcom: Extend RPMh power controller driver to
 register warming devices.

On Thu 19 Mar 18:41 PDT 2020, Thara Gopinath wrote:

> RPMh power control hosts power domains that can be used as
> thermal warming devices. Register these power domains
> with the generic power domain warming device thermal framework.
> 
> Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
> Signed-off-by: Thara Gopinath <thara.gopinath@...aro.org>
> ---
> 
> v3->v4:
> 	- Introduce a boolean value is_warming_dev in rpmhpd structure to
> 	  indicate if a generic power domain can be used as a warming
> 	  device or not.With this change, device tree no longer has to
> 	  specify which power domain inside the rpmh power domain provider
> 	  is a warming device.
> 	- Move registering of warming devices into a late initcall to
> 	  ensure that warming devices are registered after thermal
> 	  framework is initialized.

This information is lost when we merge patches, as such I would like
such design decisions to be described in the commit message itself.
But...

> 
>  drivers/soc/qcom/rpmhpd.c | 37 ++++++++++++++++++++++++++++++++++++-
>  1 file changed, 36 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/qcom/rpmhpd.c b/drivers/soc/qcom/rpmhpd.c
> index 7142409a3b77..4e9c0bbb8826 100644
> --- a/drivers/soc/qcom/rpmhpd.c
> +++ b/drivers/soc/qcom/rpmhpd.c
> @@ -11,6 +11,7 @@
>  #include <linux/of_device.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_opp.h>
> +#include <linux/pd_warming.h>
>  #include <soc/qcom/cmd-db.h>
>  #include <soc/qcom/rpmh.h>
>  #include <dt-bindings/power/qcom-rpmpd.h>
> @@ -48,6 +49,7 @@ struct rpmhpd {
>  	bool		enabled;
>  	const char	*res_name;
>  	u32		addr;
> +	bool		is_warming_dev;
>  };
>  
>  struct rpmhpd_desc {
> @@ -55,6 +57,8 @@ struct rpmhpd_desc {
>  	size_t num_pds;
>  };
>  
> +const struct rpmhpd_desc *global_desc;
> +
>  static DEFINE_MUTEX(rpmhpd_lock);
>  
>  /* SDM845 RPMH powerdomains */
> @@ -89,6 +93,7 @@ static struct rpmhpd sdm845_mx = {
>  	.pd = { .name = "mx", },
>  	.peer = &sdm845_mx_ao,
>  	.res_name = "mx.lvl",
> +	.is_warming_dev = true,
>  };
>  
>  static struct rpmhpd sdm845_mx_ao = {
> @@ -452,7 +457,14 @@ static int rpmhpd_probe(struct platform_device *pdev)
>  					       &rpmhpds[i]->pd);
>  	}
>  
> -	return of_genpd_add_provider_onecell(pdev->dev.of_node, data);
> +	ret = of_genpd_add_provider_onecell(pdev->dev.of_node, data);
> +
> +	if (ret)
> +		return ret;
> +
> +	global_desc = desc;
> +
> +	return 0;
>  }
>  
>  static struct platform_driver rpmhpd_driver = {
> @@ -469,3 +481,26 @@ static int __init rpmhpd_init(void)
>  	return platform_driver_register(&rpmhpd_driver);
>  }
>  core_initcall(rpmhpd_init);
> +
> +static int __init rpmhpd_init_warming_device(void)
> +{
> +	size_t num_pds;
> +	struct rpmhpd **rpmhpds;
> +	int i;
> +
> +	if (!global_desc)
> +		return -EINVAL;
> +
> +	rpmhpds = global_desc->rpmhpds;
> +	num_pds = global_desc->num_pds;
> +
> +	if (!of_find_property(rpmhpds[0]->dev->of_node, "#cooling-cells", NULL))
> +		return 0;
> +
> +	for (i = 0; i < num_pds; i++)
> +		if (rpmhpds[i]->is_warming_dev)
> +			of_pd_warming_register(rpmhpds[i]->dev, i);
> +
> +	return 0;
> +}
> +late_initcall(rpmhpd_init_warming_device);

...why can't this be done in rpmhpd_probe()?

In particular with the recent patches from John Stultz to allow rpmhpd
to be built as a module I don't think there's any guarantees that
rpmh_probe() will have succeeded before rpmhpd_init_warming_device()
executes.

Regards,
Bjorn