Re: [PATCH V2 7/8] ARM: cpuidle: Register per cpuidle device

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On 03/19/2015 04:31 PM, Lina Iyer wrote:
On Wed, Mar 18 2015 at 12:46 -0600, Daniel Lezcano wrote:
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@xxxxxxxxxx>
---
drivers/cpuidle/cpuidle-arm.c | 45
+++++++++++++++++++++++++++++++++++++++++--
1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-arm.c
b/drivers/cpuidle/cpuidle-arm.c
index 1c94b88..0682ed0 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);

Is a per-cpu variable needed? There seems to be no per-cpu access, other
than at init.

:)

Actually it is the cpuidle framework which is using the per cpu variable.

+
/*
 * arm_enter_idle_state - Programs CPU to enter the specified state
 *
@@ -94,6 +97,7 @@ static int __init arm_idle_init(void)
{
    int cpu, ret;
    struct cpuidle_driver *drv = &arm_idle_driver;
+    struct cpuidle_device *dev;

    /*
     * Initialize idle states data, starting at index 1.
@@ -105,18 +109,55 @@ 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;
+            goto out_fail;
+        }
+
+        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+        if (!dev) {
+            pr_err("Failed to allocate cpuidle device\n");
+            goto out_fail;
+        }
+
+        dev->cpu = cpu;
+        per_cpu(cpuidle_arm_dev, cpu) = dev;
+
+        ret = cpuidle_register_device(dev);
+        if (ret) {
+            pr_err("Failed to register cpuidle device for CPU %d\n",
+                   cpu);
+            kfree(dev);
+            goto out_fail;
        }
    }
+out:
+    return ret;

-    return cpuidle_register(drv, NULL);
+out_fail:
+    for (cpu--; cpu <= 0; cpu--) {
+        dev = per_cpu(cpuidle_arm_dev, cpu);
+        cpuidle_unregister_device(dev);
+        kfree(dev);
+    }
+    cpuidle_unregister_driver(drv);
+    goto out;
}
device_initcall(arm_idle_init);
--
1.9.1



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