Re: [PATCH v3 1/2] clk: Add generic sync_state callback for disabling unused clocks

[Bjorn Andersson]

On Tue, Dec 27, 2022 at 10:45:27PM +0200, Abel Vesa wrote:
> There are unused clocks that need to remain untouched by clk_disable_unused,
> and most likely could be disabled later on sync_state. So 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,
> skip disabling its clocks.
> 
> Signed-off-by: Abel Vesa <abel.vesa@xxxxxxxxxx>

Reviewed-by: Bjorn Andersson <andersson@xxxxxxxxxx>

Regards,
Bjorn

> ---
> 
> Changes since v2:
>  * dropped the check for sync_state callback (clk_sync_state_disable_unused),
>    like Dmitry suggested
> 
>  drivers/clk/clk.c            | 57 +++++++++++++++++++++++++++++-------
>  include/linux/clk-provider.h |  1 +
>  2 files changed, 47 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index e62552a75f08..ac7182903d88 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1302,14 +1302,26 @@ 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)
>  {
> +	bool from_sync_state = !!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 (from_sync_state && core->dev != dev)
> +		return;
> +
> +	/*
> +	 * clock will be unprepared on sync_state,
> +	 * so leave as is for now
> +	 */
> +	if (!from_sync_state && dev_has_sync_state(core->dev))
> +		return;
>  
>  	if (core->prepare_count)
>  		return;
> @@ -1332,15 +1344,27 @@ 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)
>  {
> +	bool from_sync_state = !!dev;
>  	struct clk_core *child;
>  	unsigned long flags;
>  
>  	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 (from_sync_state && core->dev != dev)
> +		return;
> +
> +	/*
> +	 * clock will be disabled on sync_state,
> +	 * so leave as is for now
> +	 */
> +	if (!from_sync_state && dev_has_sync_state(core->dev))
> +		return;
>  
>  	if (core->flags & CLK_OPS_PARENT_ENABLE)
>  		clk_core_prepare_enable(core->parent);
> @@ -1378,7 +1402,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
>  		clk_core_disable_unprepare(core->parent);
>  }
>  
> -static bool clk_ignore_unused __initdata;
> +static bool clk_ignore_unused;
>  static int __init clk_ignore_unused_setup(char *__unused)
>  {
>  	clk_ignore_unused = true;
> @@ -1386,35 +1410,46 @@ 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;
> +		return;
>  	}
>  
>  	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)
> +{
> +	__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 842e72a5348f..cf1adfeaf257 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -720,6 +720,7 @@ 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
> -- 
> 2.34.1
>