Re: [PATCH v2 1/2] clk: Add generic sync_state callback for disabling unused clocks
From: Dmitry Baryshkov
Date: Sun Dec 25 2022 - 19:55:41 EST
On Sun, 25 Dec 2022 at 18:47, Abel Vesa <abel.vesa@xxxxxxxxxx> 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>
> ---
>
> Changes since v1:
> * Dropped the 0 returned by __clk_disable_unused when clk_ignore_unused
> is set.
> * Dropped __initdata for clk_ignore_unused
>
> drivers/clk/clk.c | 59 +++++++++++++++++++++++++++++-------
> include/linux/clk-provider.h | 1 +
> 2 files changed, 49 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index e62552a75f08..5185b857fc65 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -1302,14 +1302,27 @@ 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) &&
> + core->dev->driver->sync_state == clk_sync_state_disable_unused)
I link the overall approach, but I don't think we should check the
sync_state function.
Such a check would disallow a driver to wrap the
clk_sync_state_disable_unused() into some driver-specific code.
> + return;
>
> if (core->prepare_count)
> return;
> @@ -1332,15 +1345,28 @@ 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 &&
> + core->dev->driver->sync_state == clk_sync_state_disable_unused)
> + return;
>
> if (core->flags & CLK_OPS_PARENT_ENABLE)
> clk_core_prepare_enable(core->parent);
> @@ -1378,7 +1404,7 @@ 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 +1412,46 @@ 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
>
--
With best wishes
Dmitry