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Date: Tue, 27 Dec 2022 21:16:38 +0200
From: Abel Vesa <abel.vesa@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Mike Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
Andy Gross <agross@...nel.org>,
Bjorn Andersson <andersson@...nel.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>,
linux-clk@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH v2 1/2] clk: Add generic sync_state callback for
disabling unused clocks
On 22-12-26 02:54:22, Dmitry Baryshkov wrote:
> On Sun, 25 Dec 2022 at 18:47, Abel Vesa <abel.vesa@...aro.org> 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@...aro.org>
> > ---
> >
> > 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.
OK, will drop it and resend.
>
> > + 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
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