clock helper for determining flags properties

The patch provides a helper to get flags properties of a clock node.

Signed-off-by Gabriel Fernandez <[email protected]>

---
 drivers/clk/clk.c            | 11 +++++++++++
 include/linux/clk-provider.h |  6 ++++++
 2 files changed, 17 insertions(+)

drivers/clk/clk.c +0 -0

index 4d56220..cae8985 100644

drivers/clk/clk.c +5 -0

+
+	return flags;
+}
+EXPORT_SYMBOL_GPL(of_clk_get_flags);
+
 struct clock_provider {
 	of_clk_init_cb_t clk_init_cb;
 	struct device_node *np;

include/linux/clk-provider.h +6 -0

index 59e2eb5..650bc10 100644
@@ -519,6 +519,7 @@ int of_clk_get_parent_count(struct device_node *np);
 const char *of_clk_get_parent_name(struct device_node *np, int index);
 
 void of_clk_init(const struct of_device_id *matches);
+unsigned long of_clk_get_flags(struct device_node *np);
 
 #else /* !CONFIG_OF */
 

@@ -546,6 +547,11 @@ static inline const char *of_clk_get_parent_name(struct device_node *np,
 {
 	return NULL;
 }
+static inline unsigned long of_clk_get_flags(struct device_node *np)
+{
+	return NULL;
+}
+
 #define of_clk_init(matches) \
 	{ while (0); }
 #endif /* CONFIG_OF */

Signature · 1 line

1.9.1

Quoted 14 lines · Gabriel FERNANDEZ

The patch provides a helper to get flags properties of a clock node.

Signed-off-by Gabriel Fernandez <[email protected]>

---
  drivers/clk/clk.c            | 11 +++++++++++
  include/linux/clk-provider.h |  6 ++++++
  2 files changed, 17 insertions(+)

drivers/clk/clk.c +0 -0

index 4d56220..cae8985 100644

drivers/clk/clk.c const char *of_clk_get_parent_name(struct device_node *np, int index) · line 2536

Quoted 9 lines

drivers/clk/clk.c +6 -0

@@ -2528,6 +2528,17 @@ const char *of_clk_get_parent_name(struct device_node *np, int index)
  }
  EXPORT_SYMBOL_GPL(of_clk_get_parent_name);
 
+unsigned long of_clk_get_flags(struct device_node *np)
+{
+	unsigned long flags = 0;
+
+	if (of_property_read_bool(np, "set-rate-parent"))
+		flags |= CLK_SET_RATE_PARENT;

NAK.

This is _not_ a hardware property. This flag describes internals of the Linux clock framework, and is thus not suitable for DT.

You've also failed to document the property.

What are you trying to achieve here, and why do you think this is the best way of achieving that?

Quoted 33 lines

drivers/clk/clk.c +5 -0

+
+	return flags;
+}
+EXPORT_SYMBOL_GPL(of_clk_get_flags);
+
  struct clock_provider {
  	of_clk_init_cb_t clk_init_cb;
  	struct device_node *np;

include/linux/clk-provider.h +6 -1

index 59e2eb5..650bc10 100644
@@ -519,6 +519,7 @@ int of_clk_get_parent_count(struct device_node *np);
  const char *of_clk_get_parent_name(struct device_node *np, int index);
 
  void of_clk_init(const struct of_device_id *matches);
+unsigned long of_clk_get_flags(struct device_node *np);
 
  #else /* !CONFIG_OF */
 

@@ -546,6 +547,11 @@ static inline const char *of_clk_get_parent_name(struct device_node *np,
  {
  	return NULL;
  }
+static inline unsigned long of_clk_get_flags(struct device_node *np)
+{
+	return NULL;
+}
+
  #define of_clk_init(matches) \
  	{ while (0); }
  #endif /* CONFIG_OF */
--

Quoted 3 lines

1.9.1

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Quoted 27 lines · Gabriel FERNANDEZ

Quoted 14 lines

The patch provides a helper to get flags properties of a clock node.

Signed-off-by Gabriel Fernandez <[email protected]>

---
  drivers/clk/clk.c            | 11 +++++++++++
  include/linux/clk-provider.h |  6 ++++++
  2 files changed, 17 insertions(+)

drivers/clk/clk.c +0 -0

index 4d56220..cae8985 100644

drivers/clk/clk.c const char *of_clk_get_parent_name(struct device_node *np, int index) · line 2536

Quoted 9 lines

drivers/clk/clk.c +6 -0

@@ -2528,6 +2528,17 @@ const char *of_clk_get_parent_name(struct device_node *np, int index)
  }
  EXPORT_SYMBOL_GPL(of_clk_get_parent_name);
 
+unsigned long of_clk_get_flags(struct device_node *np)
+{
+    unsigned long flags = 0;
+
+    if (of_property_read_bool(np, "set-rate-parent"))
+            flags |= CLK_SET_RATE_PARENT;

NAK.

Quoted 2 lines

This is _not_ a hardware property. This flag describes internals of the Linux clock framework, and is thus not suitable for DT.

Mark,

while I agree above property is not a hardware property, it is at least some kind of use-case property. If not by DT, we will have to allow some way to describe master-slave relationships between clocks in a driver independent way.

Quoted 5 lines

You've also failed to document the property.

What are you trying to achieve here, and why do you think this is the best way of achieving that?

I cannot tell from the commit msgs, but consider clk-si5351 which is a driver for an external programmable clock with N PLLs and M outputs. Now connect a video clock consumer and an audio clock consumer to two different outputs and those to one PLL (as you want audio clock derived from video clock, typical HDMI scenario).

Now, there should be a way to tell the generic driver which outputs are allowed to change the PLLs rate and which don't. Otherwise, the clock chip would be pretty useless as e.g. your audio clock consumer will overwrite the rate the video clock consumer has chosen.

BTW, clk-si5351 has vendor-specific properties to specify which output clocks are pll-masters for some kernel cycles already.

Sebastian

Quoted 42 lines

Quoted 33 lines

drivers/clk/clk.c +5 -0

+
+    return flags;
+}
+EXPORT_SYMBOL_GPL(of_clk_get_flags);
+
  struct clock_provider {
     of_clk_init_cb_t clk_init_cb;
     struct device_node *np;

include/linux/clk-provider.h +6 -1

index 59e2eb5..650bc10 100644
@@ -519,6 +519,7 @@ int of_clk_get_parent_count(struct device_node *np);
  const char *of_clk_get_parent_name(struct device_node *np, int index);
 
  void of_clk_init(const struct of_device_id *matches);
+unsigned long of_clk_get_flags(struct device_node *np);
 
  #else /* !CONFIG_OF */
 

@@ -546,6 +547,11 @@ static inline const char *of_clk_get_parent_name(struct device_node *np,
  {
     return NULL;
  }
+static inline unsigned long of_clk_get_flags(struct device_node *np)
+{
+    return NULL;
+}
+
  #define of_clk_init(matches) \
     { while (0); }
  #endif /* CONFIG_OF */
--

Quoted 3 lines

1.9.1

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Quoting Sebastian Hesselbarth (2014-05-13 08:11:55)

Quoted 12 lines · Mark Rutland

Quoted 4 lines

You've also failed to document the property.

What are you trying to achieve here, and why do you think this is the best way of achieving that?

I cannot tell from the commit msgs, but consider clk-si5351 which is a driver for an external programmable clock with N PLLs and M outputs. Now connect a video clock consumer and an audio clock consumer to two different outputs and those to one PLL (as you want audio clock derived from video clock, typical HDMI scenario).

Quoted 4 lines

Now, there should be a way to tell the generic driver which outputs are allowed to change the PLLs rate and which don't. Otherwise, the clock chip would be pretty useless as e.g. your audio clock consumer will overwrite the rate the video clock consumer has chosen.

This is really a job for the "coordinated clock rate changes" that are currently in development. These specify clock sub-tree snapshots of parent and rate configurations that are predefined. These combinations can be specified in DT. That helps a lot with clock configurations that change per board, or for cases where many combinations of parents and dividers can yield the same output rate, but only a subset of those were validated by the silicon validation team or had proper timing closure so we don't want to rely on the "walk up the tree" algorithm.

Quoting Sebastian Hesselbarth (2014-05-13 08:11:55)

Quoted 31 lines · Mark Rutland

Quoted 27 lines · Gabriel FERNANDEZ

Quoted 14 lines

The patch provides a helper to get flags properties of a clock node.

Signed-off-by Gabriel Fernandez <[email protected]>

---
  drivers/clk/clk.c            | 11 +++++++++++
  include/linux/clk-provider.h |  6 ++++++
  2 files changed, 17 insertions(+)

drivers/clk/clk.c +0 -0

index 4d56220..cae8985 100644

drivers/clk/clk.c const char *of_clk_get_parent_name(struct device_node *np, int index) · line 2536

Quoted 9 lines

drivers/clk/clk.c +6 -0

@@ -2528,6 +2528,17 @@ const char *of_clk_get_parent_name(struct device_node *np, int index)
  }
  EXPORT_SYMBOL_GPL(of_clk_get_parent_name);
 
+unsigned long of_clk_get_flags(struct device_node *np)
+{
+    unsigned long flags = 0;
+
+    if (of_property_read_bool(np, "set-rate-parent"))
+            flags |= CLK_SET_RATE_PARENT;

NAK.

Quoted 2 lines

This is _not_ a hardware property. This flag describes internals of the Linux clock framework, and is thus not suitable for DT.

Quoted 6 lines

Mark,

while I agree above property is not a hardware property, it is at least some kind of use-case property. If not by DT, we will have to allow some way to describe master-slave relationships between clocks in a driver independent way.

I agree with Mark.

Generally this stuff belongs in a clock driver. Of course there are the integration issues you pointed out. More on that below.

As an aside, CLK_SET_RATE_PARENT is a headache, since propagation of the operation up to the parent clock really should be the default behavior for .set_rate (and in fact this is the case for the new-ish .determine_rate op). Some history on those decisions can be found at [1] and [2].

Quoted 12 lines

Quoted 5 lines

You've also failed to document the property.

What are you trying to achieve here, and why do you think this is the best way of achieving that?

I cannot tell from the commit msgs, but consider clk-si5351 which is a driver for an external programmable clock with N PLLs and M outputs. Now connect a video clock consumer and an audio clock consumer to two different outputs and those to one PLL (as you want audio clock derived from video clock, typical HDMI scenario).

Quoted 4 lines

Now, there should be a way to tell the generic driver which outputs are allowed to change the PLLs rate and which don't. Otherwise, the clock chip would be pretty useless as e.g. your audio clock consumer will overwrite the rate the video clock consumer has chosen.

This is really a job for the "coordinated clock rate changes" that are currently in development. These specify clock sub-tree snapshots of parent and rate configurations that are predefined. These combinations can be specified in DT. That helps a lot with clock configurations that change per board, or for cases where many combinations of parents and dividers can yield the same output rate, but only a subset of those were validated by the silicon validation team or had proper timing closure so we don't want to rely on the "walk up the tree" algorithm.

Regards,
Mike

Hi,

Quoted 41 lines · Mike Turquette

Quoting Sebastian Hesselbarth (2014-05-13 08:11:55)

Quoted 31 lines · Mark Rutland

Quoted 27 lines · Gabriel FERNANDEZ

Quoted 14 lines

The patch provides a helper to get flags properties of a clock node.

Signed-off-by Gabriel Fernandez <[email protected]>

---
  drivers/clk/clk.c            | 11 +++++++++++
  include/linux/clk-provider.h |  6 ++++++
  2 files changed, 17 insertions(+)

drivers/clk/clk.c +0 -0

index 4d56220..cae8985 100644

drivers/clk/clk.c const char *of_clk_get_parent_name(struct device_node *np, int index) · line 2536

Quoted 9 lines

drivers/clk/clk.c +6 -0

@@ -2528,6 +2528,17 @@ const char *of_clk_get_parent_name(struct device_node *np, int index)
  }
  EXPORT_SYMBOL_GPL(of_clk_get_parent_name);
 
+unsigned long of_clk_get_flags(struct device_node *np)
+{
+    unsigned long flags = 0;
+
+    if (of_property_read_bool(np, "set-rate-parent"))
+            flags |= CLK_SET_RATE_PARENT;

NAK.

Quoted 2 lines

This is _not_ a hardware property. This flag describes internals of the Linux clock framework, and is thus not suitable for DT.

Quoted 6 lines

Mark,

while I agree above property is not a hardware property, it is at least some kind of use-case property. If not by DT, we will have to allow some way to describe master-slave relationships between clocks in a driver independent way.

I agree with Mark.

Quoted 9 lines

Generally this stuff belongs in a clock driver. Of course there are the integration issues you pointed out. More on that below.

As an aside, CLK_SET_RATE_PARENT is a headache, since propagation of the operation up to the parent clock really should be the default behavior for .set_rate (and in fact this is the case for the new-ish .determine_rate op). Some history on those decisions can be found at [1] and [2].

My issue is exactly the same as Marc, it's for solve some case with PCM and HDMI clocks.

Quoted 26 lines

Quoted 12 lines

Quoted 5 lines

You've also failed to document the property.

What are you trying to achieve here, and why do you think this is the best way of achieving that?

I cannot tell from the commit msgs, but consider clk-si5351 which is a driver for an external programmable clock with N PLLs and M outputs. Now connect a video clock consumer and an audio clock consumer to two different outputs and those to one PLL (as you want audio clock derived from video clock, typical HDMI scenario).

Quoted 4 lines

Now, there should be a way to tell the generic driver which outputs are allowed to change the PLLs rate and which don't. Otherwise, the clock chip would be pretty useless as e.g. your audio clock consumer will overwrite the rate the video clock consumer has chosen.

This is really a job for the "coordinated clock rate changes" that are currently in development. These specify clock sub-tree snapshots of parent and rate configurations that are predefined. These combinations can be specified in DT. That helps a lot with clock configurations that change per board, or for cases where many combinations of parents and dividers can yield the same output rate, but only a subset of those were validated by the silicon validation team or had proper timing closure so we don't want to rely on the "walk up the tree" algorithm.

Quoted 2 lines

Regards,
Mike

Ok i think this work will be the best solutions for my issue.

Where i can find some threads about that ?

Thanks a lot.

Best Regards.

Gabriel.