diff mbox series

[RFC,1/2] clk: Add generic sync_state callback for disabling unused clocks

Message ID 20220706150411.708213-1-abel.vesa@linaro.org (mailing list archive)
State Not Applicable
Headers show
Series [RFC,1/2] clk: Add generic sync_state callback for disabling unused clocks | expand

Commit Message

Abel Vesa July 6, 2022, 3:04 p.m. UTC
There are unused clocks that need to stay enabled on clk_disable_unused,
but rather should be disabled later on on sync_state. Provide a generic
sync_state callback for the clock providers that register such clocks.
Then, use the same mechanism as clk_disable_unused from that generic
callback, but pass the device to make sure only the clocks belonging to
the current clock provider get disabled, if unused. Also, during the
default clk_disable_unused, if the driver that registered the clock has
the generic clk_sync_state_disable_unused callback set for sync_state,
leave its clocks enabled.

Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
---
 drivers/clk/clk.c            | 67 +++++++++++++++++++++++++++---------
 include/linux/clk-provider.h |  1 +
 2 files changed, 52 insertions(+), 16 deletions(-)

Comments

Abel Vesa July 21, 2022, 8:19 a.m. UTC | #1
On 22-07-06 18:04:10, Abel Vesa wrote:
> There are unused clocks that need to stay enabled on clk_disable_unused,
> but rather should be disabled later on on sync_state. Provide a generic
> sync_state callback for the clock providers that register such clocks.
> Then, use the same mechanism as clk_disable_unused from that generic
> callback, but pass the device to make sure only the clocks belonging to
> the current clock provider get disabled, if unused. Also, during the
> default clk_disable_unused, if the driver that registered the clock has
> the generic clk_sync_state_disable_unused callback set for sync_state,
> leave its clocks enabled.
>
> Signed-off-by: Abel Vesa <abel.vesa@linaro.org>

Gentle ping.

> ---
>  drivers/clk/clk.c            | 67 +++++++++++++++++++++++++++---------
>  include/linux/clk-provider.h |  1 +
>  2 files changed, 52 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 7fc191c15507..ea55806505c0 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1218,19 +1218,31 @@ static void clk_core_disable_unprepare(struct clk_core *core)
>  	clk_core_unprepare_lock(core);
>  }
>
> -static void __init clk_unprepare_unused_subtree(struct clk_core *core)
> +static void clk_unprepare_unused_subtree(struct clk_core *core,
> +						struct device *dev)
>  {
>  	struct clk_core *child;
>
>  	lockdep_assert_held(&prepare_lock);
>
>  	hlist_for_each_entry(child, &core->children, child_node)
> -		clk_unprepare_unused_subtree(child);
> +		clk_unprepare_unused_subtree(child, dev);
> +
> +	if (dev && core->dev != dev)
> +		return;
> +
> +	/*
> +	 * clock will be unprepared on sync_state,
> +	 * so leave as is on clk_disable_unused
> +	 */
> +	if (!dev && dev_has_sync_state(core->dev) &&
> +		core->dev->driver->sync_state == clk_sync_state_disable_unused)
> +		return;
>
>  	if (core->prepare_count)
>  		return;
>
> -	if (core->flags & CLK_IGNORE_UNUSED)
> +	if (!dev && core->flags & CLK_IGNORE_UNUSED)
>  		return;
>
>  	if (clk_pm_runtime_get(core))
> @@ -1248,7 +1260,8 @@ static void __init clk_unprepare_unused_subtree(struct clk_core *core)
>  	clk_pm_runtime_put(core);
>  }
>
> -static void __init clk_disable_unused_subtree(struct clk_core *core)
> +static void clk_disable_unused_subtree(struct clk_core *core,
> +					struct device *dev)
>  {
>  	struct clk_core *child;
>  	unsigned long flags;
> @@ -1256,7 +1269,18 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
>  	lockdep_assert_held(&prepare_lock);
>
>  	hlist_for_each_entry(child, &core->children, child_node)
> -		clk_disable_unused_subtree(child);
> +		clk_disable_unused_subtree(child, dev);
> +
> +	if (dev && core->dev != dev)
> +		return;
> +
> +	/*
> +	 * clock will be disabled on sync_state,
> +	 * so leave as is on clk_disable_unused
> +	 */
> +	if (!dev && dev_has_sync_state(core->dev) &&
> +		core->dev->driver->sync_state == clk_sync_state_disable_unused)
> +		return;
>
>  	if (core->flags & CLK_OPS_PARENT_ENABLE)
>  		clk_core_prepare_enable(core->parent);
> @@ -1269,7 +1293,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
>  	if (core->enable_count)
>  		goto unlock_out;
>
> -	if (core->flags & CLK_IGNORE_UNUSED)
> +	if (!dev && core->flags & CLK_IGNORE_UNUSED)
>  		goto unlock_out;
>
>  	/*
> @@ -1302,35 +1326,46 @@ static int __init clk_ignore_unused_setup(char *__unused)
>  }
>  __setup("clk_ignore_unused", clk_ignore_unused_setup);
>
> -static int __init clk_disable_unused(void)
> +static void __clk_disable_unused(struct device *dev)
>  {
>  	struct clk_core *core;
>
> -	if (clk_ignore_unused) {
> -		pr_warn("clk: Not disabling unused clocks\n");
> -		return 0;
> -	}
> -
>  	clk_prepare_lock();
>
>  	hlist_for_each_entry(core, &clk_root_list, child_node)
> -		clk_disable_unused_subtree(core);
> +		clk_disable_unused_subtree(core, dev);
>
>  	hlist_for_each_entry(core, &clk_orphan_list, child_node)
> -		clk_disable_unused_subtree(core);
> +		clk_disable_unused_subtree(core, dev);
>
>  	hlist_for_each_entry(core, &clk_root_list, child_node)
> -		clk_unprepare_unused_subtree(core);
> +		clk_unprepare_unused_subtree(core, dev);
>
>  	hlist_for_each_entry(core, &clk_orphan_list, child_node)
> -		clk_unprepare_unused_subtree(core);
> +		clk_unprepare_unused_subtree(core, dev);
>
>  	clk_prepare_unlock();
> +}
> +
> +static int __init clk_disable_unused(void)
> +{
> +	if (clk_ignore_unused) {
> +		pr_warn("clk: Not disabling unused clocks\n");
> +		return 0;
> +	}
> +
> +	__clk_disable_unused(NULL);
>
>  	return 0;
>  }
>  late_initcall_sync(clk_disable_unused);
>
> +void clk_sync_state_disable_unused(struct device *dev)
> +{
> +	__clk_disable_unused(dev);
> +}
> +EXPORT_SYMBOL_GPL(clk_sync_state_disable_unused);
> +
>  static int clk_core_determine_round_nolock(struct clk_core *core,
>  					   struct clk_rate_request *req)
>  {
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 72d937c03a3e..5d3ed2b14f2c 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -679,6 +679,7 @@ struct clk *clk_register_divider_table(struct device *dev, const char *name,
>  		void __iomem *reg, u8 shift, u8 width,
>  		u8 clk_divider_flags, const struct clk_div_table *table,
>  		spinlock_t *lock);
> +void clk_sync_state_disable_unused(struct device *dev);
>  /**
>   * clk_register_divider - register a divider clock with the clock framework
>   * @dev: device registering this clock
> --
> 2.34.3
>
Bjorn Andersson Sept. 29, 2022, 3:10 p.m. UTC | #2
On Wed, Jul 06, 2022 at 06:04:10PM +0300, Abel Vesa wrote:
> There are unused clocks that need to stay enabled on clk_disable_unused,
> but rather should be disabled later on on sync_state. Provide a generic
> sync_state callback for the clock providers that register such clocks.
> Then, use the same mechanism as clk_disable_unused from that generic
> callback, but pass the device to make sure only the clocks belonging to
> the current clock provider get disabled, if unused. Also, during the
> default clk_disable_unused, if the driver that registered the clock has
> the generic clk_sync_state_disable_unused callback set for sync_state,
> leave its clocks enabled.
> 

Overall I like this, just a minor thing about ignoring CLK_IGNORE_UNUSED
from the sync_stat path below.


We've talked about this not being the whole solution, because there
might be devices that will enable/disable clocks that will be used by
later devices. It seems to me that this would be an additional issue
that needs to be fixed - so I don't have a problem with us picking this
up as a first step.

But for boards where this would be a problem there's no longer a way to
opt-out of the disabling of unused clocks. So perhaps we'd want
clk_ignore_unused to affect the sync_state based case as well?

> Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
> ---
>  drivers/clk/clk.c            | 67 +++++++++++++++++++++++++++---------
>  include/linux/clk-provider.h |  1 +
>  2 files changed, 52 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 7fc191c15507..ea55806505c0 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1218,19 +1218,31 @@ static void clk_core_disable_unprepare(struct clk_core *core)
>  	clk_core_unprepare_lock(core);
>  }
>  
> -static void __init clk_unprepare_unused_subtree(struct clk_core *core)
> +static void clk_unprepare_unused_subtree(struct clk_core *core,
> +						struct device *dev)
>  {
>  	struct clk_core *child;
>  
>  	lockdep_assert_held(&prepare_lock);
>  
>  	hlist_for_each_entry(child, &core->children, child_node)
> -		clk_unprepare_unused_subtree(child);
> +		clk_unprepare_unused_subtree(child, dev);
> +
> +	if (dev && core->dev != dev)
> +		return;
> +
> +	/*
> +	 * clock will be unprepared on sync_state,
> +	 * so leave as is on clk_disable_unused
> +	 */
> +	if (!dev && dev_has_sync_state(core->dev) &&

How about introducing a local variable bool from_sync_state = !!dev, to
make these conditionals easier to read?

> +		core->dev->driver->sync_state == clk_sync_state_disable_unused)
> +		return;
>  
>  	if (core->prepare_count)
>  		return;
>  
> -	if (core->flags & CLK_IGNORE_UNUSED)
> +	if (!dev && core->flags & CLK_IGNORE_UNUSED)

Iiuc, when being called from the sync_state path, CLK_IGNORE_UNUSED will
now be ignored (and the clock will be disabled).

We don't have a lot of users of this flag, but would it not make sense
to adhere to this flag even in that case? As a continued means to
describe a clock which shouldn't be automatically disabled...

>  		return;
>  
>  	if (clk_pm_runtime_get(core))
> @@ -1248,7 +1260,8 @@ static void __init clk_unprepare_unused_subtree(struct clk_core *core)
>  	clk_pm_runtime_put(core);
>  }
>  
> -static void __init clk_disable_unused_subtree(struct clk_core *core)
> +static void clk_disable_unused_subtree(struct clk_core *core,
> +					struct device *dev)
>  {
>  	struct clk_core *child;
>  	unsigned long flags;
> @@ -1256,7 +1269,18 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
>  	lockdep_assert_held(&prepare_lock);
>  
>  	hlist_for_each_entry(child, &core->children, child_node)
> -		clk_disable_unused_subtree(child);
> +		clk_disable_unused_subtree(child, dev);
> +
> +	if (dev && core->dev != dev)
> +		return;
> +
> +	/*
> +	 * clock will be disabled on sync_state,
> +	 * so leave as is on clk_disable_unused
> +	 */
> +	if (!dev && dev_has_sync_state(core->dev) &&
> +		core->dev->driver->sync_state == clk_sync_state_disable_unused)
> +		return;
>  
>  	if (core->flags & CLK_OPS_PARENT_ENABLE)
>  		clk_core_prepare_enable(core->parent);
> @@ -1269,7 +1293,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
>  	if (core->enable_count)
>  		goto unlock_out;
>  
> -	if (core->flags & CLK_IGNORE_UNUSED)
> +	if (!dev && core->flags & CLK_IGNORE_UNUSED)
>  		goto unlock_out;
>  
>  	/*
> @@ -1302,35 +1326,46 @@ static int __init clk_ignore_unused_setup(char *__unused)
>  }
>  __setup("clk_ignore_unused", clk_ignore_unused_setup);
>  
> -static int __init clk_disable_unused(void)
> +static void __clk_disable_unused(struct device *dev)
>  {
>  	struct clk_core *core;
>  
> -	if (clk_ignore_unused) {
> -		pr_warn("clk: Not disabling unused clocks\n");
> -		return 0;
> -	}

As mentioned above, I think it's reasonable to keep this here.

Regards,
Bjorn

> -
>  	clk_prepare_lock();
>  
>  	hlist_for_each_entry(core, &clk_root_list, child_node)
> -		clk_disable_unused_subtree(core);
> +		clk_disable_unused_subtree(core, dev);
>  
>  	hlist_for_each_entry(core, &clk_orphan_list, child_node)
> -		clk_disable_unused_subtree(core);
> +		clk_disable_unused_subtree(core, dev);
>  
>  	hlist_for_each_entry(core, &clk_root_list, child_node)
> -		clk_unprepare_unused_subtree(core);
> +		clk_unprepare_unused_subtree(core, dev);
>  
>  	hlist_for_each_entry(core, &clk_orphan_list, child_node)
> -		clk_unprepare_unused_subtree(core);
> +		clk_unprepare_unused_subtree(core, dev);
>  
>  	clk_prepare_unlock();
> +}
> +
> +static int __init clk_disable_unused(void)
> +{
> +	if (clk_ignore_unused) {
> +		pr_warn("clk: Not disabling unused clocks\n");
> +		return 0;
> +	}
> +
> +	__clk_disable_unused(NULL);
>  
>  	return 0;
>  }
>  late_initcall_sync(clk_disable_unused);
>  
> +void clk_sync_state_disable_unused(struct device *dev)
> +{
> +	__clk_disable_unused(dev);
> +}
> +EXPORT_SYMBOL_GPL(clk_sync_state_disable_unused);
> +
>  static int clk_core_determine_round_nolock(struct clk_core *core,
>  					   struct clk_rate_request *req)
>  {
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 72d937c03a3e..5d3ed2b14f2c 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -679,6 +679,7 @@ struct clk *clk_register_divider_table(struct device *dev, const char *name,
>  		void __iomem *reg, u8 shift, u8 width,
>  		u8 clk_divider_flags, const struct clk_div_table *table,
>  		spinlock_t *lock);
> +void clk_sync_state_disable_unused(struct device *dev);
>  /**
>   * clk_register_divider - register a divider clock with the clock framework
>   * @dev: device registering this clock
> -- 
> 2.34.3
>
diff mbox series

Patch

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 7fc191c15507..ea55806505c0 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1218,19 +1218,31 @@  static void clk_core_disable_unprepare(struct clk_core *core)
 	clk_core_unprepare_lock(core);
 }
 
-static void __init clk_unprepare_unused_subtree(struct clk_core *core)
+static void clk_unprepare_unused_subtree(struct clk_core *core,
+						struct device *dev)
 {
 	struct clk_core *child;
 
 	lockdep_assert_held(&prepare_lock);
 
 	hlist_for_each_entry(child, &core->children, child_node)
-		clk_unprepare_unused_subtree(child);
+		clk_unprepare_unused_subtree(child, dev);
+
+	if (dev && core->dev != dev)
+		return;
+
+	/*
+	 * clock will be unprepared on sync_state,
+	 * so leave as is on clk_disable_unused
+	 */
+	if (!dev && dev_has_sync_state(core->dev) &&
+		core->dev->driver->sync_state == clk_sync_state_disable_unused)
+		return;
 
 	if (core->prepare_count)
 		return;
 
-	if (core->flags & CLK_IGNORE_UNUSED)
+	if (!dev && core->flags & CLK_IGNORE_UNUSED)
 		return;
 
 	if (clk_pm_runtime_get(core))
@@ -1248,7 +1260,8 @@  static void __init clk_unprepare_unused_subtree(struct clk_core *core)
 	clk_pm_runtime_put(core);
 }
 
-static void __init clk_disable_unused_subtree(struct clk_core *core)
+static void clk_disable_unused_subtree(struct clk_core *core,
+					struct device *dev)
 {
 	struct clk_core *child;
 	unsigned long flags;
@@ -1256,7 +1269,18 @@  static void __init clk_disable_unused_subtree(struct clk_core *core)
 	lockdep_assert_held(&prepare_lock);
 
 	hlist_for_each_entry(child, &core->children, child_node)
-		clk_disable_unused_subtree(child);
+		clk_disable_unused_subtree(child, dev);
+
+	if (dev && core->dev != dev)
+		return;
+
+	/*
+	 * clock will be disabled on sync_state,
+	 * so leave as is on clk_disable_unused
+	 */
+	if (!dev && dev_has_sync_state(core->dev) &&
+		core->dev->driver->sync_state == clk_sync_state_disable_unused)
+		return;
 
 	if (core->flags & CLK_OPS_PARENT_ENABLE)
 		clk_core_prepare_enable(core->parent);
@@ -1269,7 +1293,7 @@  static void __init clk_disable_unused_subtree(struct clk_core *core)
 	if (core->enable_count)
 		goto unlock_out;
 
-	if (core->flags & CLK_IGNORE_UNUSED)
+	if (!dev && core->flags & CLK_IGNORE_UNUSED)
 		goto unlock_out;
 
 	/*
@@ -1302,35 +1326,46 @@  static int __init clk_ignore_unused_setup(char *__unused)
 }
 __setup("clk_ignore_unused", clk_ignore_unused_setup);
 
-static int __init clk_disable_unused(void)
+static void __clk_disable_unused(struct device *dev)
 {
 	struct clk_core *core;
 
-	if (clk_ignore_unused) {
-		pr_warn("clk: Not disabling unused clocks\n");
-		return 0;
-	}
-
 	clk_prepare_lock();
 
 	hlist_for_each_entry(core, &clk_root_list, child_node)
-		clk_disable_unused_subtree(core);
+		clk_disable_unused_subtree(core, dev);
 
 	hlist_for_each_entry(core, &clk_orphan_list, child_node)
-		clk_disable_unused_subtree(core);
+		clk_disable_unused_subtree(core, dev);
 
 	hlist_for_each_entry(core, &clk_root_list, child_node)
-		clk_unprepare_unused_subtree(core);
+		clk_unprepare_unused_subtree(core, dev);
 
 	hlist_for_each_entry(core, &clk_orphan_list, child_node)
-		clk_unprepare_unused_subtree(core);
+		clk_unprepare_unused_subtree(core, dev);
 
 	clk_prepare_unlock();
+}
+
+static int __init clk_disable_unused(void)
+{
+	if (clk_ignore_unused) {
+		pr_warn("clk: Not disabling unused clocks\n");
+		return 0;
+	}
+
+	__clk_disable_unused(NULL);
 
 	return 0;
 }
 late_initcall_sync(clk_disable_unused);
 
+void clk_sync_state_disable_unused(struct device *dev)
+{
+	__clk_disable_unused(dev);
+}
+EXPORT_SYMBOL_GPL(clk_sync_state_disable_unused);
+
 static int clk_core_determine_round_nolock(struct clk_core *core,
 					   struct clk_rate_request *req)
 {
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 72d937c03a3e..5d3ed2b14f2c 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -679,6 +679,7 @@  struct clk *clk_register_divider_table(struct device *dev, const char *name,
 		void __iomem *reg, u8 shift, u8 width,
 		u8 clk_divider_flags, const struct clk_div_table *table,
 		spinlock_t *lock);
+void clk_sync_state_disable_unused(struct device *dev);
 /**
  * clk_register_divider - register a divider clock with the clock framework
  * @dev: device registering this clock