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

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

[Abel Vesa]

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@linaro.org>
---

Here is the link to the RFC:

https://lore.kernel.org/all/20220929151047.wom3m2ydgxme5nhh@builder.lan/

Changes since RFC:
 * Added from_sync_state local variable, as Bjorn suggested
 * Dropped the addition extra condition for the CLK_IGNORE_UNUSED
 * Changed the comments above the sync_state checking
 * Moved back the clk_ignore_unused check to clk_disable_unused_subtree
 function, as Bjorn suggested

 drivers/clk/clk.c            | 55 ++++++++++++++++++++++++++++++------
 include/linux/clk-provider.h |  1 +
 2 files changed, 47 insertions(+), 9 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index c3c3f8c07258..acf5139e16d8 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1292,14 +1292,27 @@ 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)
+		return;
 
 	if (core->prepare_count)
 		return;
@@ -1322,15 +1335,28 @@ 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);
@@ -1376,7 +1402,7 @@ 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;
 
@@ -1388,23 +1414,34 @@ static int __init clk_disable_unused(void)
 	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 267cd06b54a0..06a8622f90cf 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -718,6 +718,7 @@ 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

[PATCH 2/2] clk: qcom: sdm845: Use generic clk_sync_state_disable_unused callback

[Abel Vesa]

By adding the newly added clk_sync_state_disable_unused as sync_state
callback to all sdm845 clock providers, we make sure that no clock
belonging to these providers gets disabled on clk_disable_unused,
but rather they are disabled on sync_state, when it is safe, since
all the consumers build as modules have had their chance of enabling
their own clocks.

Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
---

Changes since RFC:
 * Added Bjorn's R-b tag

 drivers/clk/qcom/camcc-sdm845.c  | 1 +
 drivers/clk/qcom/dispcc-sdm845.c | 1 +
 drivers/clk/qcom/gcc-sdm845.c    | 1 +
 drivers/clk/qcom/gpucc-sdm845.c  | 1 +
 4 files changed, 4 insertions(+)

diff --git a/drivers/clk/qcom/camcc-sdm845.c b/drivers/clk/qcom/camcc-sdm845.c
index 27d44188a7ab..e5aeb832e47b 100644
--- a/drivers/clk/qcom/camcc-sdm845.c
+++ b/drivers/clk/qcom/camcc-sdm845.c
@@ -1743,6 +1743,7 @@ static struct platform_driver cam_cc_sdm845_driver = {
 	.driver	= {
 		.name = "sdm845-camcc",
 		.of_match_table = cam_cc_sdm845_match_table,
+		.sync_state = clk_sync_state_disable_unused,
 	},
 };
 
diff --git a/drivers/clk/qcom/dispcc-sdm845.c b/drivers/clk/qcom/dispcc-sdm845.c
index 735adfefc379..1810d58bad09 100644
--- a/drivers/clk/qcom/dispcc-sdm845.c
+++ b/drivers/clk/qcom/dispcc-sdm845.c
@@ -869,6 +869,7 @@ static struct platform_driver disp_cc_sdm845_driver = {
 	.driver		= {
 		.name	= "disp_cc-sdm845",
 		.of_match_table = disp_cc_sdm845_match_table,
+		.sync_state = clk_sync_state_disable_unused,
 	},
 };
 
diff --git a/drivers/clk/qcom/gcc-sdm845.c b/drivers/clk/qcom/gcc-sdm845.c
index 6af08e0ca847..0ff05af515c4 100644
--- a/drivers/clk/qcom/gcc-sdm845.c
+++ b/drivers/clk/qcom/gcc-sdm845.c
@@ -4020,6 +4020,7 @@ static struct platform_driver gcc_sdm845_driver = {
 	.driver		= {
 		.name	= "gcc-sdm845",
 		.of_match_table = gcc_sdm845_match_table,
+		.sync_state = clk_sync_state_disable_unused,
 	},
 };
 
diff --git a/drivers/clk/qcom/gpucc-sdm845.c b/drivers/clk/qcom/gpucc-sdm845.c
index 110b54401bc6..622a54a67d32 100644
--- a/drivers/clk/qcom/gpucc-sdm845.c
+++ b/drivers/clk/qcom/gpucc-sdm845.c
@@ -205,6 +205,7 @@ static struct platform_driver gpu_cc_sdm845_driver = {
 	.driver = {
 		.name = "sdm845-gpucc",
 		.of_match_table = gpu_cc_sdm845_match_table,
+		.sync_state = clk_sync_state_disable_unused,
 	},
 };
 
-- 
2.34.1