diff mbox series

cpufreq: Remove CPUFREQ_STICKY flag

Message ID 377d2e2d328276070ae2f26c65daa1497bb3c3cf.1612166647.git.viresh.kumar@linaro.org (mailing list archive)
State New
Headers show
Series cpufreq: Remove CPUFREQ_STICKY flag | expand

Commit Message

Viresh Kumar Feb. 1, 2021, 8:05 a.m. UTC
During cpufreq driver's registration, if the ->init() callback for all
the CPUs fail then there is not much point in keeping the driver around
as it will only account for more unnecessary noise, for example cpufreq
core will try to suspend/resume the driver which never got registered
properly.

The removal of such a driver is avoided if the driver carries the
CPUFREQ_STICKY flag. This was added way back [1] in 2004 and perhaps no
one should ever need it now. A lot of driver do set this flag, probably
because they just copied it from another driver.

Remove the flag and update the relevant drivers.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/include/linux/cpufreq.h?id=7cc9f0d9a1ab04cedc60d64fd8dcf7df224a3b4d

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq-dt.c           |  2 +-
 drivers/cpufreq/cpufreq.c              |  3 +--
 drivers/cpufreq/davinci-cpufreq.c      |  2 +-
 drivers/cpufreq/loongson1-cpufreq.c    |  2 +-
 drivers/cpufreq/mediatek-cpufreq.c     |  2 +-
 drivers/cpufreq/omap-cpufreq.c         |  2 +-
 drivers/cpufreq/qcom-cpufreq-hw.c      |  2 +-
 drivers/cpufreq/s3c24xx-cpufreq.c      |  2 +-
 drivers/cpufreq/s5pv210-cpufreq.c      |  2 +-
 drivers/cpufreq/sa1100-cpufreq.c       |  2 +-
 drivers/cpufreq/sa1110-cpufreq.c       |  2 +-
 drivers/cpufreq/scmi-cpufreq.c         |  2 +-
 drivers/cpufreq/scpi-cpufreq.c         |  2 +-
 drivers/cpufreq/spear-cpufreq.c        |  2 +-
 drivers/cpufreq/tegra186-cpufreq.c     |  2 +-
 drivers/cpufreq/tegra194-cpufreq.c     |  3 +--
 drivers/cpufreq/vexpress-spc-cpufreq.c |  3 +--
 include/linux/cpufreq.h                | 17 +++++++----------
 18 files changed, 24 insertions(+), 30 deletions(-)

Comments

Dominik Brodowski Feb. 1, 2021, 9:44 a.m. UTC | #1
Viresh,

Am Mon, Feb 01, 2021 at 01:35:51PM +0530 schrieb Viresh Kumar:
> The removal of such a driver is avoided if the driver carries the
> CPUFREQ_STICKY flag. This was added way back [1] in 2004 and perhaps no
> one should ever need it now. A lot of driver do set this flag, probably
> because they just copied it from another driver.

IIRC, it was required on various ARM systems,[*] as CPUs were registered as
subsys_initcall(), while cpufreq used to be initialized only later, as an
arch_initcall(). If the ordering is opposite now on all architectures (it
wasn't on ARM back then), we should be fine.

[*] https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/arch/arm/mach-sa1100/cpu-sa1100.c?id=f59d3bbe35f6268d729f51be82af8325d62f20f5

Thanks,
	Dominik
Viresh Kumar Feb. 1, 2021, 10:05 a.m. UTC | #2
On 01-02-21, 10:44, Dominik Brodowski wrote:
> IIRC, it was required on various ARM systems,[*] as CPUs were registered as
> subsys_initcall(), while cpufreq used to be initialized only later, as an

s/later/earlier ? arch happens before subsys not at least and that is
the only way we can break cpufreq here, i.e. when the driver comes up
before the CPUs are registered.

> arch_initcall(). If the ordering is opposite now on all architectures (it
> wasn't on ARM back then), we should be fine.
> 
> [*] https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/arch/arm/mach-sa1100/cpu-sa1100.c?id=f59d3bbe35f6268d729f51be82af8325d62f20f5

Thanks for your reply, it made me look at that aspect in some more
detail to confirm I don't end up breaking anything. Unless I am making
a mistake in reading the code, this is the code flow that we have
right now:

start_kernel()
-> kernel_init()
   -> kernel_init_freeable()
      -> do_basic_setup()
         -> driver_init()
            -> cpu_dev_init()
               -> subsys_system_register(for-CPUs)
 
         -> do_initcalls()
            -> register-cpufreq-driver from any level

And so CPUs should always be there for a cpufreq driver.

Makes sense ?
Rafael J. Wysocki Feb. 1, 2021, 2:02 p.m. UTC | #3
On Mon, Feb 1, 2021 at 11:06 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 01-02-21, 10:44, Dominik Brodowski wrote:
> > IIRC, it was required on various ARM systems,[*] as CPUs were registered as
> > subsys_initcall(), while cpufreq used to be initialized only later, as an
>
> s/later/earlier ? arch happens before subsys not at least and that is
> the only way we can break cpufreq here, i.e. when the driver comes up
> before the CPUs are registered.
>
> > arch_initcall(). If the ordering is opposite now on all architectures (it
> > wasn't on ARM back then), we should be fine.
> >
> > [*] https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/arch/arm/mach-sa1100/cpu-sa1100.c?id=f59d3bbe35f6268d729f51be82af8325d62f20f5
>
> Thanks for your reply, it made me look at that aspect in some more
> detail to confirm I don't end up breaking anything. Unless I am making
> a mistake in reading the code, this is the code flow that we have
> right now:
>
> start_kernel()
> -> kernel_init()
>    -> kernel_init_freeable()
>       -> do_basic_setup()
>          -> driver_init()
>             -> cpu_dev_init()
>                -> subsys_system_register(for-CPUs)
>
>          -> do_initcalls()
>             -> register-cpufreq-driver from any level
>
> And so CPUs should always be there for a cpufreq driver.
>
> Makes sense ?

It does to me, but can you update the changelog, please?
diff mbox series

Patch

diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c
index ad4234518ef6..b1e1bdc63b01 100644
--- a/drivers/cpufreq/cpufreq-dt.c
+++ b/drivers/cpufreq/cpufreq-dt.c
@@ -175,7 +175,7 @@  static int cpufreq_exit(struct cpufreq_policy *policy)
 }
 
 static struct cpufreq_driver dt_cpufreq_driver = {
-	.flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
+	.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 		 CPUFREQ_IS_COOLING_DEV,
 	.verify = cpufreq_generic_frequency_table_verify,
 	.target_index = set_target,
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index d0a3525ce27f..7d0ae968def7 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2810,8 +2810,7 @@  int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	if (ret)
 		goto err_boost_unreg;
 
-	if (!(cpufreq_driver->flags & CPUFREQ_STICKY) &&
-	    list_empty(&cpufreq_policy_list)) {
+	if (unlikely(list_empty(&cpufreq_policy_list))) {
 		/* if all ->init() calls failed, unregister */
 		ret = -ENODEV;
 		pr_debug("%s: No CPU initialized for driver %s\n", __func__,
diff --git a/drivers/cpufreq/davinci-cpufreq.c b/drivers/cpufreq/davinci-cpufreq.c
index 91f477a6cbc4..9e97f60f8199 100644
--- a/drivers/cpufreq/davinci-cpufreq.c
+++ b/drivers/cpufreq/davinci-cpufreq.c
@@ -95,7 +95,7 @@  static int davinci_cpu_init(struct cpufreq_policy *policy)
 }
 
 static struct cpufreq_driver davinci_driver = {
-	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify		= cpufreq_generic_frequency_table_verify,
 	.target_index	= davinci_target,
 	.get		= cpufreq_generic_get,
diff --git a/drivers/cpufreq/loongson1-cpufreq.c b/drivers/cpufreq/loongson1-cpufreq.c
index 86f612593e49..fb72d709db56 100644
--- a/drivers/cpufreq/loongson1-cpufreq.c
+++ b/drivers/cpufreq/loongson1-cpufreq.c
@@ -116,7 +116,7 @@  static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
 
 static struct cpufreq_driver ls1x_cpufreq_driver = {
 	.name		= "cpufreq-ls1x",
-	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify		= cpufreq_generic_frequency_table_verify,
 	.target_index	= ls1x_cpufreq_target,
 	.get		= cpufreq_generic_get,
diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index 022e3e966e71..f2e491b25b07 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -463,7 +463,7 @@  static int mtk_cpufreq_exit(struct cpufreq_policy *policy)
 }
 
 static struct cpufreq_driver mtk_cpufreq_driver = {
-	.flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
+	.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 		 CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 		 CPUFREQ_IS_COOLING_DEV,
 	.verify = cpufreq_generic_frequency_table_verify,
diff --git a/drivers/cpufreq/omap-cpufreq.c b/drivers/cpufreq/omap-cpufreq.c
index 3694bb030df3..e035ee216b0f 100644
--- a/drivers/cpufreq/omap-cpufreq.c
+++ b/drivers/cpufreq/omap-cpufreq.c
@@ -144,7 +144,7 @@  static int omap_cpu_exit(struct cpufreq_policy *policy)
 }
 
 static struct cpufreq_driver omap_driver = {
-	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify		= cpufreq_generic_frequency_table_verify,
 	.target_index	= omap_target,
 	.get		= cpufreq_generic_get,
diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
index 7df18903b66c..f3b4e471e898 100644
--- a/drivers/cpufreq/qcom-cpufreq-hw.c
+++ b/drivers/cpufreq/qcom-cpufreq-hw.c
@@ -374,7 +374,7 @@  static struct freq_attr *qcom_cpufreq_hw_attr[] = {
 };
 
 static struct cpufreq_driver cpufreq_qcom_hw_driver = {
-	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 			  CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 			  CPUFREQ_IS_COOLING_DEV,
 	.verify		= cpufreq_generic_frequency_table_verify,
diff --git a/drivers/cpufreq/s3c24xx-cpufreq.c b/drivers/cpufreq/s3c24xx-cpufreq.c
index 37efc0dc3f91..7380c32b238e 100644
--- a/drivers/cpufreq/s3c24xx-cpufreq.c
+++ b/drivers/cpufreq/s3c24xx-cpufreq.c
@@ -420,7 +420,7 @@  static int s3c_cpufreq_resume(struct cpufreq_policy *policy)
 #endif
 
 static struct cpufreq_driver s3c24xx_driver = {
-	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.target		= s3c_cpufreq_target,
 	.get		= cpufreq_generic_get,
 	.init		= s3c_cpufreq_init,
diff --git a/drivers/cpufreq/s5pv210-cpufreq.c b/drivers/cpufreq/s5pv210-cpufreq.c
index bed496cf8d24..69786e5bbf05 100644
--- a/drivers/cpufreq/s5pv210-cpufreq.c
+++ b/drivers/cpufreq/s5pv210-cpufreq.c
@@ -574,7 +574,7 @@  static int s5pv210_cpufreq_reboot_notifier_event(struct notifier_block *this,
 }
 
 static struct cpufreq_driver s5pv210_driver = {
-	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify		= cpufreq_generic_frequency_table_verify,
 	.target_index	= s5pv210_target,
 	.get		= cpufreq_generic_get,
diff --git a/drivers/cpufreq/sa1100-cpufreq.c b/drivers/cpufreq/sa1100-cpufreq.c
index 5c075ef6adc0..252b9fc26124 100644
--- a/drivers/cpufreq/sa1100-cpufreq.c
+++ b/drivers/cpufreq/sa1100-cpufreq.c
@@ -186,7 +186,7 @@  static int __init sa1100_cpu_init(struct cpufreq_policy *policy)
 }
 
 static struct cpufreq_driver sa1100_driver __refdata = {
-	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 			  CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
 	.verify		= cpufreq_generic_frequency_table_verify,
 	.target_index	= sa1100_target,
diff --git a/drivers/cpufreq/sa1110-cpufreq.c b/drivers/cpufreq/sa1110-cpufreq.c
index d9d04d935b3a..1a83c8678a63 100644
--- a/drivers/cpufreq/sa1110-cpufreq.c
+++ b/drivers/cpufreq/sa1110-cpufreq.c
@@ -310,7 +310,7 @@  static int __init sa1110_cpu_init(struct cpufreq_policy *policy)
 /* sa1110_driver needs __refdata because it must remain after init registers
  * it with cpufreq_register_driver() */
 static struct cpufreq_driver sa1110_driver __refdata = {
-	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 			  CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
 	.verify		= cpufreq_generic_frequency_table_verify,
 	.target_index	= sa1110_target,
diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
index 491a0a24fb1e..5bd03b59887f 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -217,7 +217,7 @@  static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
 
 static struct cpufreq_driver scmi_cpufreq_driver = {
 	.name	= "scmi",
-	.flags	= CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
+	.flags	= CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 		  CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 		  CPUFREQ_IS_COOLING_DEV,
 	.verify	= cpufreq_generic_frequency_table_verify,
diff --git a/drivers/cpufreq/scpi-cpufreq.c b/drivers/cpufreq/scpi-cpufreq.c
index e5140ad63db8..d6a698a1b5d1 100644
--- a/drivers/cpufreq/scpi-cpufreq.c
+++ b/drivers/cpufreq/scpi-cpufreq.c
@@ -191,7 +191,7 @@  static int scpi_cpufreq_exit(struct cpufreq_policy *policy)
 
 static struct cpufreq_driver scpi_cpufreq_driver = {
 	.name	= "scpi-cpufreq",
-	.flags	= CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
+	.flags	= CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 		  CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 		  CPUFREQ_IS_COOLING_DEV,
 	.verify	= cpufreq_generic_frequency_table_verify,
diff --git a/drivers/cpufreq/spear-cpufreq.c b/drivers/cpufreq/spear-cpufreq.c
index 73bd8dc47074..7d0d62a06bf3 100644
--- a/drivers/cpufreq/spear-cpufreq.c
+++ b/drivers/cpufreq/spear-cpufreq.c
@@ -160,7 +160,7 @@  static int spear_cpufreq_init(struct cpufreq_policy *policy)
 
 static struct cpufreq_driver spear_cpufreq_driver = {
 	.name		= "cpufreq-spear",
-	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify		= cpufreq_generic_frequency_table_verify,
 	.target_index	= spear_cpufreq_target,
 	.get		= cpufreq_generic_get,
diff --git a/drivers/cpufreq/tegra186-cpufreq.c b/drivers/cpufreq/tegra186-cpufreq.c
index e566ea298b59..5d1943e787b0 100644
--- a/drivers/cpufreq/tegra186-cpufreq.c
+++ b/drivers/cpufreq/tegra186-cpufreq.c
@@ -117,7 +117,7 @@  static unsigned int tegra186_cpufreq_get(unsigned int cpu)
 
 static struct cpufreq_driver tegra186_cpufreq_driver = {
 	.name = "tegra186",
-	.flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
+	.flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 			CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.get = tegra186_cpufreq_get,
 	.verify = cpufreq_generic_frequency_table_verify,
diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
index 6a67f36f3b80..a9620e4489ae 100644
--- a/drivers/cpufreq/tegra194-cpufreq.c
+++ b/drivers/cpufreq/tegra194-cpufreq.c
@@ -272,8 +272,7 @@  static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
 
 static struct cpufreq_driver tegra194_cpufreq_driver = {
 	.name = "tegra194",
-	.flags = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS |
-		CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify = cpufreq_generic_frequency_table_verify,
 	.target_index = tegra194_cpufreq_set_target,
 	.get = tegra194_get_speed,
diff --git a/drivers/cpufreq/vexpress-spc-cpufreq.c b/drivers/cpufreq/vexpress-spc-cpufreq.c
index f711d8eaea6a..51dfa9ae6cf5 100644
--- a/drivers/cpufreq/vexpress-spc-cpufreq.c
+++ b/drivers/cpufreq/vexpress-spc-cpufreq.c
@@ -486,8 +486,7 @@  static void ve_spc_cpufreq_ready(struct cpufreq_policy *policy)
 
 static struct cpufreq_driver ve_spc_cpufreq_driver = {
 	.name			= "vexpress-spc",
-	.flags			= CPUFREQ_STICKY |
-					CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
+	.flags			= CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 					CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 	.verify			= cpufreq_generic_frequency_table_verify,
 	.target_index		= ve_spc_cpufreq_set_target,
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 9c8b7437b6cd..c8e40e91fe9b 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -387,8 +387,13 @@  struct cpufreq_driver {
 
 /* flags */
 
-/* driver isn't removed even if all ->init() calls failed */
-#define CPUFREQ_STICKY				BIT(0)
+/*
+ * Set by drivers that need to update internale upper and lower boundaries along
+ * with the target frequency and so the core and governors should also invoke
+ * the diver if the target frequency does not change, but the policy min or max
+ * may have changed.
+ */
+#define CPUFREQ_NEED_UPDATE_LIMITS		BIT(0)
 
 /* loops_per_jiffy or other kernel "constants" aren't affected by frequency transitions */
 #define CPUFREQ_CONST_LOOPS			BIT(1)
@@ -432,14 +437,6 @@  struct cpufreq_driver {
  */
 #define CPUFREQ_IS_COOLING_DEV			BIT(7)
 
-/*
- * Set by drivers that need to update internale upper and lower boundaries along
- * with the target frequency and so the core and governors should also invoke
- * the diver if the target frequency does not change, but the policy min or max
- * may have changed.
- */
-#define CPUFREQ_NEED_UPDATE_LIMITS		BIT(8)
-
 int cpufreq_register_driver(struct cpufreq_driver *driver_data);
 int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);