drivers/rtc/rtc-pcf85063.c | 6 ++++++ 1 file changed, 6 insertions(+)
From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
The PCF85063 powers up with its CLKOUT pin driving the 32.768 kHz. While
it's possible to request a specific default frequency in the DT via
assigned-clocks/assigned-clock-rates on the RTC node itself, even without
a real consumer referencing the clock, there is no such possibility to
disable the clock output by default.
Therefore gate CLKOUT in the driver before registering the OF provider,
mirroring the pcf8563 and hym8563 siblings which already force an off state
at registration. Doing it before devm_of_clk_add_hw_provider() leaves the
real consumers in the device tree free to re-enable the output afterwards,
while an otherwise unused CLKOUT now stays off.
In practice it means that with CLKOUT disabled the RTC consumes around
250nA at 25°C and 6-10uA with CLKOUT enabled (5v Vdd). Which means days vs
hours on a supercapacitor.
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
---
drivers/rtc/rtc-pcf85063.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
index 01e209d88f5f3..0b6d8083b6456 100644
--- a/drivers/rtc/rtc-pcf85063.c
+++ b/drivers/rtc/rtc-pcf85063.c
@@ -523,6 +523,12 @@ static struct clk *pcf85063_clkout_register_clk(struct pcf85063 *pcf85063)
/* optional override of the clockname */
of_property_read_string(node, "clock-output-names", &init.name);
+ /* power-on default is the 32768 Hz output on; gate it until claimed */
+ ret = regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL2,
+ PCF85063_REG_CLKO_F_MASK, PCF85063_REG_CLKO_F_OFF);
+ if (ret)
+ return ret;
+
/* register the clock */
clk = devm_clk_register(&pcf85063->rtc->dev, &pcf85063->clkout_hw);
--
2.55.0
Hi Sverdlin,
kernel test robot noticed the following build errors:
[auto build test ERROR on abelloni/rtc-next]
[also build test ERROR on linus/master v7.2 next-20260824]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/A-Sverdlin/rtc-pcf85063-disable-the-clkout-output-by-default/20260824-100759
base: https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git rtc-next
patch link: https://lore.kernel.org/r/20260824080801.709764-1-alexander.sverdlin%40siemens.com
patch subject: [PATCH] rtc: pcf85063: disable the clkout output by default
config: arm-randconfig-003-20260826 (https://download.01.org/0day-ci/archive/20260826/202608260642.ydlr9qYE-lkp@intel.com/config)
compiler: clang version 24.0.0git (https://github.com/llvm/llvm-project 771bdfdab2d66a4eb85b8ea7673cfa30152718b1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260826/202608260642.ydlr9qYE-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202608260642.ydlr9qYE-lkp@intel.com/
All errors (new ones prefixed by >>):
>> drivers/rtc/rtc-pcf85063.c:527:2: error: use of undeclared identifier 'ret'
527 | ret = regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL2,
| ^~~
drivers/rtc/rtc-pcf85063.c:529:6: error: use of undeclared identifier 'ret'
529 | if (ret)
| ^~~
drivers/rtc/rtc-pcf85063.c:530:10: error: use of undeclared identifier 'ret'
530 | return ret;
| ^~~
3 errors generated.
vim +/ret +527 drivers/rtc/rtc-pcf85063.c
497
498 static struct clk *pcf85063_clkout_register_clk(struct pcf85063 *pcf85063)
499 {
500 struct clk *clk;
501 struct clk_init_data init = {};
502 struct device_node *node = pcf85063->rtc->dev.parent->of_node;
503 struct device_node *fixed_clock;
504
505 fixed_clock = of_get_child_by_name(node, "clock");
506 if (fixed_clock) {
507 /*
508 * skip registering square wave clock when a fixed
509 * clock has been registered. The fixed clock is
510 * registered automatically when being referenced.
511 */
512 of_node_put(fixed_clock);
513 return NULL;
514 }
515
516 init.name = "pcf85063-clkout";
517 init.ops = &pcf85063_clkout_ops;
518 init.flags = 0;
519 init.parent_names = NULL;
520 init.num_parents = 0;
521 pcf85063->clkout_hw.init = &init;
522
523 /* optional override of the clockname */
524 of_property_read_string(node, "clock-output-names", &init.name);
525
526 /* power-on default is the 32768 Hz output on; gate it until claimed */
> 527 ret = regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL2,
528 PCF85063_REG_CLKO_F_MASK, PCF85063_REG_CLKO_F_OFF);
529 if (ret)
530 return ret;
531
532 /* register the clock */
533 clk = devm_clk_register(&pcf85063->rtc->dev, &pcf85063->clkout_hw);
534
535 if (!IS_ERR(clk))
536 of_clk_add_provider(node, of_clk_src_simple_get, clk);
537
538 return clk;
539 }
540 #endif
541
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Hi Sverdlin,
kernel test robot noticed the following build errors:
[auto build test ERROR on abelloni/rtc-next]
[also build test ERROR on linus/master v7.2 next-20260824]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/A-Sverdlin/rtc-pcf85063-disable-the-clkout-output-by-default/20260824-100759
base: https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux.git rtc-next
patch link: https://lore.kernel.org/r/20260824080801.709764-1-alexander.sverdlin%40siemens.com
patch subject: [PATCH] rtc: pcf85063: disable the clkout output by default
config: nios2-allmodconfig (https://download.01.org/0day-ci/archive/20260826/202608260554.ivtsRrZ9-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 11.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260826/202608260554.ivtsRrZ9-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202608260554.ivtsRrZ9-lkp@intel.com/
All errors (new ones prefixed by >>):
drivers/rtc/rtc-pcf85063.c: In function 'pcf85063_clkout_register_clk':
>> drivers/rtc/rtc-pcf85063.c:527:9: error: 'ret' undeclared (first use in this function); did you mean 'net'?
527 | ret = regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL2,
| ^~~
| net
drivers/rtc/rtc-pcf85063.c:527:9: note: each undeclared identifier is reported only once for each function it appears in
vim +527 drivers/rtc/rtc-pcf85063.c
497
498 static struct clk *pcf85063_clkout_register_clk(struct pcf85063 *pcf85063)
499 {
500 struct clk *clk;
501 struct clk_init_data init = {};
502 struct device_node *node = pcf85063->rtc->dev.parent->of_node;
503 struct device_node *fixed_clock;
504
505 fixed_clock = of_get_child_by_name(node, "clock");
506 if (fixed_clock) {
507 /*
508 * skip registering square wave clock when a fixed
509 * clock has been registered. The fixed clock is
510 * registered automatically when being referenced.
511 */
512 of_node_put(fixed_clock);
513 return NULL;
514 }
515
516 init.name = "pcf85063-clkout";
517 init.ops = &pcf85063_clkout_ops;
518 init.flags = 0;
519 init.parent_names = NULL;
520 init.num_parents = 0;
521 pcf85063->clkout_hw.init = &init;
522
523 /* optional override of the clockname */
524 of_property_read_string(node, "clock-output-names", &init.name);
525
526 /* power-on default is the 32768 Hz output on; gate it until claimed */
> 527 ret = regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL2,
528 PCF85063_REG_CLKO_F_MASK, PCF85063_REG_CLKO_F_OFF);
529 if (ret)
530 return ret;
531
532 /* register the clock */
533 clk = devm_clk_register(&pcf85063->rtc->dev, &pcf85063->clkout_hw);
534
535 if (!IS_ERR(clk))
536 of_clk_add_provider(node, of_clk_src_simple_get, clk);
537
538 return clk;
539 }
540 #endif
541
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
On 24/08/2026 10:07:59+0200, A. Sverdlin wrote: > From: Alexander Sverdlin <alexander.sverdlin@siemens.com> > > The PCF85063 powers up with its CLKOUT pin driving the 32.768 kHz. While > it's possible to request a specific default frequency in the DT via > assigned-clocks/assigned-clock-rates on the RTC node itself, even without > a real consumer referencing the clock, there is no such possibility to > disable the clock output by default. Are you sure about this? The CCF should disable the clock if it is not used. > > Therefore gate CLKOUT in the driver before registering the OF provider, > mirroring the pcf8563 and hym8563 siblings which already force an off state > at registration. Doing it before devm_of_clk_add_hw_provider() leaves the > real consumers in the device tree free to re-enable the output afterwards, > while an otherwise unused CLKOUT now stays off. > > In practice it means that with CLKOUT disabled the RTC consumes around > 250nA at 25°C and 6-10uA with CLKOUT enabled (5v Vdd). Which means days vs > hours on a supercapacitor. > > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com> > --- > drivers/rtc/rtc-pcf85063.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c > index 01e209d88f5f3..0b6d8083b6456 100644 > --- a/drivers/rtc/rtc-pcf85063.c > +++ b/drivers/rtc/rtc-pcf85063.c > @@ -523,6 +523,12 @@ static struct clk *pcf85063_clkout_register_clk(struct pcf85063 *pcf85063) > /* optional override of the clockname */ > of_property_read_string(node, "clock-output-names", &init.name); > > + /* power-on default is the 32768 Hz output on; gate it until claimed */ > + ret = regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL2, > + PCF85063_REG_CLKO_F_MASK, PCF85063_REG_CLKO_F_OFF); > + if (ret) > + return ret; > + > /* register the clock */ > clk = devm_clk_register(&pcf85063->rtc->dev, &pcf85063->clkout_hw); > > -- > 2.55.0 > -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
Hi Alexandre, On Mon, 2026-08-24 at 10:24 +0200, Alexandre Belloni wrote: > > From: Alexander Sverdlin <alexander.sverdlin@siemens.com> > > > > The PCF85063 powers up with its CLKOUT pin driving the 32.768 kHz. While > > it's possible to request a specific default frequency in the DT via > > assigned-clocks/assigned-clock-rates on the RTC node itself, even without > > a real consumer referencing the clock, there is no such possibility to > > disable the clock output by default. > > Are you sure about this? The CCF should disable the clock if it is not > used. There is late_initcall_sync(clk_disable_unused) (marked __init), but for the clock providers registered later, say, via modules, there is no such mechanism. And I double-checked this putting some debug prints into the driver, nothing from struct clk_ops is being called without a consumer in DT. > > Therefore gate CLKOUT in the driver before registering the OF provider, > > mirroring the pcf8563 and hym8563 siblings which already force an off state > > at registration. Doing it before devm_of_clk_add_hw_provider() leaves the > > real consumers in the device tree free to re-enable the output afterwards, > > while an otherwise unused CLKOUT now stays off. > > > > In practice it means that with CLKOUT disabled the RTC consumes around > > 250nA at 25°C and 6-10uA with CLKOUT enabled (5v Vdd). Which means days vs > > hours on a supercapacitor. > > > > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com> > > --- > > drivers/rtc/rtc-pcf85063.c | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c > > index 01e209d88f5f3..0b6d8083b6456 100644 > > --- a/drivers/rtc/rtc-pcf85063.c > > +++ b/drivers/rtc/rtc-pcf85063.c > > @@ -523,6 +523,12 @@ static struct clk *pcf85063_clkout_register_clk(struct pcf85063 *pcf85063) > > /* optional override of the clockname */ > > of_property_read_string(node, "clock-output-names", &init.name); > > > > + /* power-on default is the 32768 Hz output on; gate it until claimed */ > > + ret = regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL2, > > + PCF85063_REG_CLKO_F_MASK, PCF85063_REG_CLKO_F_OFF); > > + if (ret) > > + return ret; > > + > > /* register the clock */ > > clk = devm_clk_register(&pcf85063->rtc->dev, &pcf85063->clkout_hw); > > > > -- > > 2.55.0 > > -- Alexander Sverdlin Siemens AG www.siemens.com
On 24/08/2026 09:58:16+0000, Sverdlin, Alexander wrote:
> Hi Alexandre,
>
> On Mon, 2026-08-24 at 10:24 +0200, Alexandre Belloni wrote:
> > > From: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> > >
> > > The PCF85063 powers up with its CLKOUT pin driving the 32.768 kHz. While
> > > it's possible to request a specific default frequency in the DT via
> > > assigned-clocks/assigned-clock-rates on the RTC node itself, even without
> > > a real consumer referencing the clock, there is no such possibility to
> > > disable the clock output by default.
> >
> > Are you sure about this? The CCF should disable the clock if it is not
> > used.
>
> There is late_initcall_sync(clk_disable_unused) (marked __init), but for the
> clock providers registered later, say, via modules, there is no such mechanism.
> And I double-checked this putting some debug prints into the driver,
> nothing from struct clk_ops is being called without a consumer in DT.
>
Right, so what about the patch attached which seems to work fine with my
rv3032.
> > > Therefore gate CLKOUT in the driver before registering the OF provider,
> > > mirroring the pcf8563 and hym8563 siblings which already force an off state
> > > at registration. Doing it before devm_of_clk_add_hw_provider() leaves the
> > > real consumers in the device tree free to re-enable the output afterwards,
> > > while an otherwise unused CLKOUT now stays off.
> > >
> > > In practice it means that with CLKOUT disabled the RTC consumes around
> > > 250nA at 25°C and 6-10uA with CLKOUT enabled (5v Vdd). Which means days vs
> > > hours on a supercapacitor.
> > >
> > > Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
> > > ---
> > > drivers/rtc/rtc-pcf85063.c | 6 ++++++
> > > 1 file changed, 6 insertions(+)
> > >
> > > diff --git a/drivers/rtc/rtc-pcf85063.c b/drivers/rtc/rtc-pcf85063.c
> > > index 01e209d88f5f3..0b6d8083b6456 100644
> > > --- a/drivers/rtc/rtc-pcf85063.c
> > > +++ b/drivers/rtc/rtc-pcf85063.c
> > > @@ -523,6 +523,12 @@ static struct clk *pcf85063_clkout_register_clk(struct pcf85063 *pcf85063)
> > > /* optional override of the clockname */
> > > of_property_read_string(node, "clock-output-names", &init.name);
> > >
> > > + /* power-on default is the 32768 Hz output on; gate it until claimed */
> > > + ret = regmap_update_bits(pcf85063->regmap, PCF85063_REG_CTRL2,
> > > + PCF85063_REG_CLKO_F_MASK, PCF85063_REG_CLKO_F_OFF);
> > > + if (ret)
> > > + return ret;
> > > +
> > > /* register the clock */
> > > clk = devm_clk_register(&pcf85063->rtc->dev, &pcf85063->clkout_hw);
> > >
> > > --
> > > 2.55.0
> > >
>
> --
> Alexander Sverdlin
> Siemens AG
> www.siemens.com
--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
From 68b91c1d8b64b0b9fc88b9036f9a4340e7a0a98f Mon Sep 17 00:00:00 2001
From: Alexandre Belloni <alexandre.belloni@bootlin.com>
Date: Tue, 25 Aug 2026 22:54:06 +0200
Subject: [PATCH] clk: disable unused clocks registered after boot
clk_disable_unused() only runs once as a late_initcall, so clocks
registered afterwards by loading a module are never checked and may be left
running needlessly.
So record when clk_disable_unused has run and afterwards, schedule a
delayed work to run the scan when new clocks are registered.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
drivers/clk/clk.c | 50 +++++++++++++++++++++++++++++++++++------------
1 file changed, 37 insertions(+), 13 deletions(-)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 048adfa86a5d..817f916192ac 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -24,6 +24,7 @@
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/stringhash.h>
+#include <linux/workqueue.h>
#include "clk.h"
@@ -47,6 +48,10 @@ static LIST_HEAD(clk_notifier_list);
static HLIST_HEAD(clk_rpm_list);
static DEFINE_MUTEX(clk_rpm_list_lock);
+static bool clk_disable_unused_done;
+
+#define CLK_DISABLE_UNUSED_DELAY (HZ / 2)
+
static const struct hlist_head *all_lists[] = {
&clk_root_list,
&clk_orphan_list,
@@ -1442,7 +1447,7 @@ 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 clk_core *child;
@@ -1467,7 +1472,7 @@ static void __init clk_unprepare_unused_subtree(struct clk_core *core)
}
}
-static void __init clk_disable_unused_subtree(struct clk_core *core)
+static void clk_disable_unused_subtree(struct clk_core *core)
{
struct clk_core *child;
unsigned long flags;
@@ -1516,21 +1521,14 @@ 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(void)
{
struct clk_core *core;
int ret;
- if (clk_ignore_unused) {
- pr_warn("clk: Not disabling unused clocks\n");
- return 0;
- }
-
- pr_info("clk: Disabling unused clocks\n");
-
ret = clk_pm_runtime_get_all();
if (ret)
- return ret;
+ return;
/*
* Grab the prepare lock to keep the clk topology stable while iterating
* over clks.
@@ -1552,10 +1550,31 @@ static int __init clk_disable_unused(void)
clk_prepare_unlock();
clk_pm_runtime_put_all();
+}
+
+static void clk_disable_unused_workfn(struct work_struct *work)
+{
+ clk_disable_unused();
+}
+
+static DECLARE_DELAYED_WORK(clk_disable_unused_work, clk_disable_unused_workfn);
+
+static int __init clk_disable_unused_init(void)
+{
+ if (clk_ignore_unused) {
+ pr_warn("clk: Not disabling unused clocks\n");
+ return 0;
+ }
+
+ pr_info("clk: Disabling unused clocks\n");
+
+ clk_disable_unused();
+
+ WRITE_ONCE(clk_disable_unused_done, true);
return 0;
}
-late_initcall_sync(clk_disable_unused);
+late_initcall_sync(clk_disable_unused_init);
static int clk_core_determine_round_nolock(struct clk_core *core,
struct clk_rate_request *req)
@@ -4366,8 +4385,13 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw)
clk_core_link_consumer(core, hw->clk);
ret = __clk_core_init(core);
- if (!ret)
+ if (!ret) {
+ if (READ_ONCE(clk_disable_unused_done))
+ mod_delayed_work(system_power_efficient_wq,
+ &clk_disable_unused_work,
+ CLK_DISABLE_UNUSED_DELAY);
return hw->clk;
+ }
clk_prepare_lock();
clk_core_unlink_consumer(hw->clk);
--
2.55.0
Hi Alexandre, On Tue, 2026-08-25 at 23:07 +0200, Alexandre Belloni wrote: > > > > The PCF85063 powers up with its CLKOUT pin driving the 32.768 kHz. While > > > > it's possible to request a specific default frequency in the DT via > > > > assigned-clocks/assigned-clock-rates on the RTC node itself, even without > > > > a real consumer referencing the clock, there is no such possibility to > > > > disable the clock output by default. > > > > > > Are you sure about this? The CCF should disable the clock if it is not > > > used. > > > > There is late_initcall_sync(clk_disable_unused) (marked __init), but for the > > clock providers registered later, say, via modules, there is no such mechanism. > > And I double-checked this putting some debug prints into the driver, > > nothing from struct clk_ops is being called without a consumer in DT. > > > > Right, so what about the patch attached which seems to work fine with my > rv3032. The patch would work for me as well, will you publish it officially? BTW, it's racy, if __clk_register() would be called between clk_disable_unused(); ... and... WRITE_ONCE(clk_disable_unused_done, true); ... the workqueue will not be scheduled. But overall it's a nice idea! Maybe we just need to drop late_initcall_sync() entirely, this would simplify the things a bit? -- Alexander Sverdlin Siemens AG www.siemens.com
On 26/08/2026 06:13:08+0000, Sverdlin, Alexander wrote: > Hi Alexandre, > > On Tue, 2026-08-25 at 23:07 +0200, Alexandre Belloni wrote: > > > > > The PCF85063 powers up with its CLKOUT pin driving the 32.768 kHz. While > > > > > it's possible to request a specific default frequency in the DT via > > > > > assigned-clocks/assigned-clock-rates on the RTC node itself, even without > > > > > a real consumer referencing the clock, there is no such possibility to > > > > > disable the clock output by default. > > > > > > > > Are you sure about this? The CCF should disable the clock if it is not > > > > used. > > > > > > There is late_initcall_sync(clk_disable_unused) (marked __init), but for the > > > clock providers registered later, say, via modules, there is no such mechanism. > > > And I double-checked this putting some debug prints into the driver, > > > nothing from struct clk_ops is being called without a consumer in DT. > > > > > > > Right, so what about the patch attached which seems to work fine with my > > rv3032. > > The patch would work for me as well, will you publish it officially? > > BTW, it's racy, if __clk_register() would be called between > > clk_disable_unused(); > > ... and... > > WRITE_ONCE(clk_disable_unused_done, true); > > ... the workqueue will not be scheduled. But overall it's a nice idea! > > Maybe we just need to drop late_initcall_sync() entirely, this would simplify > the things a bit? > I forgot to copy you but Bryan asked whether this works for you: https://lore.kernel.org/linux-clk/20260626-clk-sync-state-v1-0-4156d8196dc8@redhat.com/ -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
On 26/08/2026 06:13:08+0000, Sverdlin, Alexander wrote: > Hi Alexandre, > > On Tue, 2026-08-25 at 23:07 +0200, Alexandre Belloni wrote: > > > > > The PCF85063 powers up with its CLKOUT pin driving the 32.768 kHz. While > > > > > it's possible to request a specific default frequency in the DT via > > > > > assigned-clocks/assigned-clock-rates on the RTC node itself, even without > > > > > a real consumer referencing the clock, there is no such possibility to > > > > > disable the clock output by default. > > > > > > > > Are you sure about this? The CCF should disable the clock if it is not > > > > used. > > > > > > There is late_initcall_sync(clk_disable_unused) (marked __init), but for the > > > clock providers registered later, say, via modules, there is no such mechanism. > > > And I double-checked this putting some debug prints into the driver, > > > nothing from struct clk_ops is being called without a consumer in DT. > > > > > > > Right, so what about the patch attached which seems to work fine with my > > rv3032. > > The patch would work for me as well, will you publish it officially? > Yes, that's the plan. > BTW, it's racy, if __clk_register() would be called between > > clk_disable_unused(); > > ... and... > > WRITE_ONCE(clk_disable_unused_done, true); > > ... the workqueue will not be scheduled. But overall it's a nice idea! I'm not sure you can actually load modules before late_initcall_sync finishes. > > Maybe we just need to drop late_initcall_sync() entirely, this would simplify > the things a bit? I'll let this to the (new) clk maintainers. -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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