cpufreq: Make cpufreq_unregister_driver() return void

All but a few drivers ignore the return value of
cpufreq_unregister_driver(). Those few that don't only call it after
cpufreq_register_driver() succeeded, in which case the call doesn't
fail.

Make the function return no value and add a WARN_ON for the case that
the function is called in an invalid situation (i.e. without a previous
successful call to cpufreq_register_driver()).
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Florian Fainelli <f.fainelli@gmail.com> # brcmstb-avs-cpufreq.c
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/amd-pstate.c

@@ -831,7 +831,7 @@ static void amd_pstate_driver_cleanup(void)
 
 static int amd_pstate_update_status(const char *buf, size_t size)
 {
-	int ret;
+	int ret = 0;
 	int mode_idx;
 
 	if (size > 7 || size < 6)
@@ -844,7 +844,7 @@ static int amd_pstate_update_status(const char *buf, size_t size)
 			return -EINVAL;
 		if (cppc_state == AMD_PSTATE_ACTIVE)
 			return -EBUSY;
-		ret = cpufreq_unregister_driver(current_pstate_driver);
+		cpufreq_unregister_driver(current_pstate_driver);
 		amd_pstate_driver_cleanup();
 		break;
 	case AMD_PSTATE_PASSIVE:

drivers/cpufreq/brcmstb-avs-cpufreq.c

@@ -751,10 +751,7 @@ static int brcm_avs_cpufreq_probe(struct platform_device *pdev)
 
 static int brcm_avs_cpufreq_remove(struct platform_device *pdev)
 {
-	int ret;
-
-	ret = cpufreq_unregister_driver(&brcm_avs_driver);
-	WARN_ON(ret);
+	cpufreq_unregister_driver(&brcm_avs_driver);
 
 	brcm_avs_prepare_uninit(pdev);
 

drivers/cpufreq/cpufreq.c

@@ -2904,12 +2904,12 @@ EXPORT_SYMBOL_GPL(cpufreq_register_driver);
  * Returns zero if successful, and -EINVAL if the cpufreq_driver is
  * currently not initialised.
  */
-int cpufreq_unregister_driver(struct cpufreq_driver *driver)
+void cpufreq_unregister_driver(struct cpufreq_driver *driver)
 {
 	unsigned long flags;
 
-	if (!cpufreq_driver || (driver != cpufreq_driver))
-		return -EINVAL;
+	if (WARN_ON(!cpufreq_driver || (driver != cpufreq_driver)))
+		return;
 
 	pr_debug("unregistering driver %s\n", driver->name);
 
@@ -2926,8 +2926,6 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
 
 	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
 	cpus_read_unlock();
-
-	return 0;
 }
 EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
 

drivers/cpufreq/davinci-cpufreq.c

@@ -138,7 +138,9 @@ static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 	if (cpufreq.asyncclk)
 		clk_put(cpufreq.asyncclk);
 
-	return cpufreq_unregister_driver(&davinci_driver);
+	cpufreq_unregister_driver(&davinci_driver);
+
+	return 0;
 }
 
 static struct platform_driver davinci_cpufreq_driver = {

drivers/cpufreq/mediatek-cpufreq-hw.c

@@ -317,7 +317,9 @@ static int mtk_cpufreq_hw_driver_probe(struct platform_device *pdev)
 
 static int mtk_cpufreq_hw_driver_remove(struct platform_device *pdev)
 {
-	return cpufreq_unregister_driver(&cpufreq_mtk_hw_driver);
+	cpufreq_unregister_driver(&cpufreq_mtk_hw_driver);
+
+	return 0;
 }
 
 static const struct of_device_id mtk_cpufreq_hw_match[] = {

drivers/cpufreq/omap-cpufreq.c

@@ -184,7 +184,9 @@ static int omap_cpufreq_probe(struct platform_device *pdev)
 
 static int omap_cpufreq_remove(struct platform_device *pdev)
 {
-	return cpufreq_unregister_driver(&omap_driver);
+	cpufreq_unregister_driver(&omap_driver);
+
+	return 0;
 }
 
 static struct platform_driver omap_cpufreq_platdrv = {

drivers/cpufreq/qcom-cpufreq-hw.c

@@ -768,7 +768,9 @@ static int qcom_cpufreq_hw_driver_probe(struct platform_device *pdev)
 
 static int qcom_cpufreq_hw_driver_remove(struct platform_device *pdev)
 {
-	return cpufreq_unregister_driver(&cpufreq_qcom_hw_driver);
+	cpufreq_unregister_driver(&cpufreq_qcom_hw_driver);
+
+	return 0;
 }
 
 static struct platform_driver qcom_cpufreq_hw_driver = {

include/linux/cpufreq.h

@@ -448,7 +448,7 @@ struct cpufreq_driver {
 #define CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING	BIT(6)
 
 int cpufreq_register_driver(struct cpufreq_driver *driver_data);
-int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
+void cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
 
 bool cpufreq_driver_test_flags(u16 flags);
 const char *cpufreq_get_current_driver(void);