[RFC,v15,01/11] ARM: cpuidle: Register per cpuidle device

Message ID 1425914206-22295-2-git-send-email-lina.iyer@linaro.org
State New
Headers show

Commit Message

Lina Iyer March 9, 2015, 3:16 p.m.
From: Daniel Lezcano <daniel.lezcano@linaro.org>

Some architectures have some cpus which does not support idle states.

Let the underlying low level code to return -ENOSYS when it is not
possible to set an idle state.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
[Minor clean ups and fixes of the per-cpu variable]
---
 drivers/cpuidle/cpuidle-arm.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

Comments

Lina Iyer March 9, 2015, 9:40 p.m. | #1
On Mon, Mar 09 2015 at 15:29 -0600, Andy Gross wrote:
>On Mon, Mar 09, 2015 at 09:16:36AM -0600, Lina Iyer wrote:
>> From: Daniel Lezcano <daniel.lezcano@linaro.org>
>>
>> Some architectures have some cpus which does not support idle states.
>>
>> Let the underlying low level code to return -ENOSYS when it is not
>> possible to set an idle state.
>>
>> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
>> [Minor clean ups and fixes of the per-cpu variable]
>> ---
>>  drivers/cpuidle/cpuidle-arm.c | 34 +++++++++++++++++++++++++++++++++-
>>  1 file changed, 33 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
>> index 1c94b88..f7cdb73 100644
>> --- a/drivers/cpuidle/cpuidle-arm.c
>> +++ b/drivers/cpuidle/cpuidle-arm.c
>> @@ -17,11 +17,14 @@
>>  #include <linux/kernel.h>
>>  #include <linux/module.h>
>>  #include <linux/of.h>
>> +#include <linux/slab.h>
>>
>>  #include <asm/cpuidle.h>
>>
>>  #include "dt_idle_states.h"
>>
>> +static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);
>> +
>>  /*
>>   * arm_enter_idle_state - Programs CPU to enter the specified state
>>   *
>> @@ -93,6 +96,7 @@ static const struct of_device_id arm_idle_state_match[] __initconst = {
>>  static int __init arm_idle_init(void)
>>  {
>>  	int cpu, ret;
>> +	struct cpuidle_device *dev;
>>  	struct cpuidle_driver *drv = &arm_idle_driver;
>>
>>  	/*
>> @@ -105,18 +109,46 @@ static int __init arm_idle_init(void)
>>  	if (ret <= 0)
>>  		return ret ? : -ENODEV;
>>
>> +
>> +	ret = cpuidle_register_driver(drv);
>> +	if (ret) {
>> +		pr_err("Failed to register cpuidle driver\n");
>> +		return ret;
>> +	}
>> +
>>  	/*
>>  	 * Call arch CPU operations in order to initialize
>>  	 * idle states suspend back-end specific data
>>  	 */
>>  	for_each_possible_cpu(cpu) {
>> +
>>  		ret = arm_cpuidle_init(cpu);
>> +		/*
>> +		 * This cpu does not support any idle states
>> +		 */
>> +		if (ret == -ENOSYS)
>> +			continue;
>> +
>>  		if (ret) {
>>  			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
>>  			return ret;
>>  		}
>> +
>> +		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>
>devm_kzalloc?  Otherwise, failures could lead to lost memory.
>
I dont have a local device to work with for allocation. May be I can get
the cpu device node and the device therefore for allocation. Thoughts?

>> +		if (!dev)
>> +			return -ENOMEM;
>> +
>> +		dev->cpu = cpu;
>> +		ret = cpuidle_register_device(dev);
>> +		if (ret) {
>> +			pr_err("Failed to register cpuidle device for CPU %d\n",
>> +			       cpu);
>> +			return ret;
>> +		}
>> +
>> +		per_cpu(cpuidle_arm_dev, cpu) = dev;
>>  	}
>>
>> -	return cpuidle_register(drv, NULL);
>> +	return 0;
>>  }
>>  device_initcall(arm_idle_init);
>> --
>> 2.1.0
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>
>-- 
>Qualcomm Innovation Center, Inc.
>The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>a Linux Foundation Collaborative Project
>
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Lina Iyer March 10, 2015, 2:57 p.m. | #2
On Tue, Mar 10 2015 at 04:37 -0600, Russell King - ARM Linux wrote:
>On Mon, Mar 09, 2015 at 09:16:36AM -0600, Lina Iyer wrote:
>> @@ -105,18 +109,46 @@ static int __init arm_idle_init(void)
>>  	if (ret <= 0)
>>  		return ret ? : -ENODEV;
>>
>> +
>
>A bit better formatting would be nice - you don't need the extra blank
>line here.
>
>> +	ret = cpuidle_register_driver(drv);
>> +	if (ret) {
>> +		pr_err("Failed to register cpuidle driver\n");
>> +		return ret;
>> +	}
>> +
>>  	/*
>>  	 * Call arch CPU operations in order to initialize
>>  	 * idle states suspend back-end specific data
>>  	 */
>>  	for_each_possible_cpu(cpu) {
>> +
>
>This blank line is not necessary either.
>
>>  		ret = arm_cpuidle_init(cpu);
>
>However, a blank line here would be a good thing.
>
Sure.
>> +		/*
>> +		 * This cpu does not support any idle states
>> +		 */
>
>Also, formatting this as /* This cpu does not support any idle states */ is
>acceptable too, and doesn't waste as many lines.
>
Will fix.
>> +		if (ret == -ENOSYS)
>> +			continue;
>> +
>>  		if (ret) {
>>  			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
>>  			return ret;
>>  		}
>> +
>> +		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>> +		if (!dev)
>> +			return -ENOMEM;
>> +
>> +		dev->cpu = cpu;
>> +		ret = cpuidle_register_device(dev);
>> +		if (ret) {
>> +			pr_err("Failed to register cpuidle device for CPU %d\n",
>> +			       cpu);
>> +			return ret;
>
>It looks like we leak the 'dev' allocation here.
>

True, I will amend that.

>Also, other error paths, it looks like we leave the previously registered
>cpuidle devices in place.  That may be acceptable if the intention is to
>initialise as many CPUs as possible - but we then miss the
>cpuidle_register() call below, which seems to make the registered devices
>useless.  It's a little inconsistent.
>
>Also, it's useful to report why something fails - printing the error code
>can help debugging if it isn't already printed elsewhere.
>
Fair point.
>> +		}
>> +
>> +		per_cpu(cpuidle_arm_dev, cpu) = dev;
>>  	}
>>
>> -	return cpuidle_register(drv, NULL);
>> +	return 0;
>>  }
>>  device_initcall(arm_idle_init);
>
>-- 
>FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
>according to speedtest.net.
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
index 1c94b88..f7cdb73 100644
--- a/drivers/cpuidle/cpuidle-arm.c
+++ b/drivers/cpuidle/cpuidle-arm.c
@@ -17,11 +17,14 @@ 
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/slab.h>
 
 #include <asm/cpuidle.h>
 
 #include "dt_idle_states.h"
 
+static DEFINE_PER_CPU(struct cpuidle_device, *cpuidle_arm_dev);
+
 /*
  * arm_enter_idle_state - Programs CPU to enter the specified state
  *
@@ -93,6 +96,7 @@  static const struct of_device_id arm_idle_state_match[] __initconst = {
 static int __init arm_idle_init(void)
 {
 	int cpu, ret;
+	struct cpuidle_device *dev;
 	struct cpuidle_driver *drv = &arm_idle_driver;
 
 	/*
@@ -105,18 +109,46 @@  static int __init arm_idle_init(void)
 	if (ret <= 0)
 		return ret ? : -ENODEV;
 
+
+	ret = cpuidle_register_driver(drv);
+	if (ret) {
+		pr_err("Failed to register cpuidle driver\n");
+		return ret;
+	}
+
 	/*
 	 * Call arch CPU operations in order to initialize
 	 * idle states suspend back-end specific data
 	 */
 	for_each_possible_cpu(cpu) {
+
 		ret = arm_cpuidle_init(cpu);
+		/*
+		 * This cpu does not support any idle states
+		 */
+		if (ret == -ENOSYS)
+			continue;
+
 		if (ret) {
 			pr_err("CPU %d failed to init idle CPU ops\n", cpu);
 			return ret;
 		}
+
+		dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+		if (!dev)
+			return -ENOMEM;
+
+		dev->cpu = cpu;
+		ret = cpuidle_register_device(dev);
+		if (ret) {
+			pr_err("Failed to register cpuidle device for CPU %d\n",
+			       cpu);
+			return ret;
+		}
+
+		per_cpu(cpuidle_arm_dev, cpu) = dev;
 	}
 
-	return cpuidle_register(drv, NULL);
+	return 0;
 }
 device_initcall(arm_idle_init);