linux-kernel - Re: [PATCH v2 1/3] clk: Fix the CLK_IGNORE

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Message-ID: <1jv7ws26a4.fsf@starbuckisacylon.baylibre.com>
Date: Tue, 12 Nov 2024 09:41:23 +0100
From: Jerome Brunet <jbrunet@...libre.com>
To: Chuan Liu via B4 Relay <devnull+chuan.liu.amlogic.com@...nel.org>
Cc: Michael Turquette <mturquette@...libre.com>,  Stephen Boyd
 <sboyd@...nel.org>,  Neil Armstrong <neil.armstrong@...aro.org>,  Kevin
 Hilman <khilman@...libre.com>,  Martin Blumenstingl
 <martin.blumenstingl@...glemail.com>,  chuan.liu@...ogic.com,
  linux-clk@...r.kernel.org,  linux-kernel@...r.kernel.org,
  linux-amlogic@...ts.infradead.org,  linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 1/3] clk: Fix the CLK_IGNORE_UNUSED failure issue

On Mon 11 Nov 2024 at 11:37, Chuan Liu via B4 Relay <devnull+chuan.liu.amlogic.com@...nel.org> wrote:

> From: Chuan Liu <chuan.liu@...ogic.com>
>
> When the clk_disable_unused_subtree() function disables an unused clock,
> if CLK_OPS_PARENT_ENABLE is configured on the clock,
> clk_core_prepare_enable() and clk_core_disable_unprepare() are called
> directly, and these two functions do not determine CLK_IGNORE_UNUSED,
> This causes the clock to be disabled even if CLK_IGNORE_UNUSED is
> configured when clk_core_disable_unprepare() is called.
>
> Two new functions clk_disable_unprepare_unused() and
> clk_prepare_enable_unused() are added to resolve the preceding
> situation. The CLK_IGNORE_UNUSED judgment logic is added to these two
> functions. To prevent clock configuration CLK_IGNORE_UNUSED from
> possible failure.
>
> Fixes: a4b3518d146f ("clk: core: support clocks which requires parents
> enable (part 1)")

Still don't think a storing the ignored state is necessary, same as v1.

> Signed-off-by: Chuan Liu <chuan.liu@...ogic.com>
> ---
>  drivers/clk/clk.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 65 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index d02451f951cf..6def76c30ce6 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -94,6 +94,7 @@ struct clk_core {
>  	struct hlist_node	debug_node;
>  #endif
>  	struct kref		ref;
> +	bool			ignore_enabled;
>  };
>  
>  #define CREATE_TRACE_POINTS
> @@ -1479,6 +1480,68 @@ static void __init clk_unprepare_unused_subtree(struct clk_core *core)
>  	}
>  }
>  
> +static void __init clk_disable_unprepare_unused(struct clk_core *core)
> +{
> +	unsigned long flags;
> +
> +	lockdep_assert_held(&prepare_lock);
> +
> +	if (!core)
> +		return;
> +
> +	if ((core->enable_count == 0) && core->ops->disable &&
> +	    !core->ignore_enabled) {
> +		flags = clk_enable_lock();
> +		core->ops->disable(core->hw);
> +		clk_enable_unlock(flags);
> +	}
> +
> +	if ((core->prepare_count == 0) && core->ops->unprepare &&
> +	    !core->ignore_enabled)
> +		core->ops->unprepare(core->hw);
> +
> +	core->ignore_enabled = false;
> +
> +	clk_disable_unprepare_unused(core->parent);
> +}
> +
> +static int __init clk_prepare_enable_unused(struct clk_core *core)
> +{
> +	int ret = 0;
> +	unsigned long flags;
> +
> +	lockdep_assert_held(&prepare_lock);
> +
> +	if (!core)
> +		return 0;
> +
> +	ret = clk_prepare_enable_unused(core->parent);
> +	if (ret)
> +		return ret;
> +
> +	if ((core->flags & CLK_IGNORE_UNUSED) && clk_core_is_enabled(core))
> +		core->ignore_enabled = true;
> +
> +	if ((core->prepare_count == 0) && core->ops->prepare) {
> +		ret = core->ops->prepare(core->hw);
> +		if (ret)
> +			goto disable_unprepare;
> +	}
> +
> +	if ((core->enable_count == 0) && core->ops->enable) {
> +		flags = clk_enable_lock();
> +		ret = core->ops->enable(core->hw);
> +		clk_enable_unlock(flags);
> +		if (ret)
> +			goto disable_unprepare;
> +	}
> +
> +	return 0;
> +disable_unprepare:
> +	clk_disable_unprepare_unused(core->parent);
> +	return ret;
> +}
> +
>  static void __init clk_disable_unused_subtree(struct clk_core *core)
>  {
>  	struct clk_core *child;
> @@ -1490,7 +1553,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
>  		clk_disable_unused_subtree(child);
>  
>  	if (core->flags & CLK_OPS_PARENT_ENABLE)
> -		clk_core_prepare_enable(core->parent);
> +		clk_prepare_enable_unused(core->parent);
>  
>  	flags = clk_enable_lock();
>  
> @@ -1517,7 +1580,7 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
>  unlock_out:
>  	clk_enable_unlock(flags);
>  	if (core->flags & CLK_OPS_PARENT_ENABLE)
> -		clk_core_disable_unprepare(core->parent);
> +		clk_disable_unprepare_unused(core->parent);
>  }
>  
>  static bool clk_ignore_unused __initdata;

-- 
Jerome