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

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Date:   Mon, 30 Mar 2020 10:53:58 -0400
From:   Thara Gopinath <thara.gopinath@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...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 3/27/20 6:53 PM, Bjorn Andersson wrote:
> 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.

It is to take care of boot order.
So this has to happen after the thermal framework is initialized. 
Thermal framework is initialized with core_initcall. Can I move the 
rpmhpd init as a postcore_initcall ? Then I can get rid of this separate 
function and keep it as part of probe.

> 
> Regards,
> Bjorn
> 

-- 
Warm Regards
Thara