ARM: l2c: add options to overwrite prefetching behavior
Subsystems (2)
PATCH v3 1/1 ARM: l2c: add options to overwrite prefetching behavior
These options make it possible to overwrites the data and instruction prefetching behavior of the arm pl310 cache controller.
---
v2: only set prefetch
v1: set prefetch and aux
Documentation/devicetree/bindings/arm/l2cc.txt | 4 ++++ arch/arm/mm/cache-l2x0.c | 20 ++++++++++++++++++++ 2 files changed, 24 insertions(+)
Documentation/devicetree/bindings/arm/l2cc.txt +4 -0
@@ -67,6 +67,10 @@ Optional properties: disable if zero. - arm,prefetch-offset : Override prefetch offset value. Valid values are 0-7, 15, 23, and 31. +- arm,prefetch-data : Enable data prefetch. Enabling prefetching + can improve performance. +- arm,prefetch-instr : Enable instruction prefetch. Enabling prefetching + can improve performance. Example:
arch/arm/mm/cache-l2x0.c +20 -0
@@ -1199,6 +1199,26 @@ static void __init l2c310_of_parse(const struct device_node *np,pr_err ("L2C-310 OF arm,prefetch-offset property value is missing\n" ); } + ret =of_property_read_u32 (np,"arm,prefetch-data" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_DATA_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_DATA_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-data property value is missing\n" ); + } + + ret =of_property_read_u32 (np,"arm,prefetch-instr" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_INSTR_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_INSTR_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-instr property value is missing\n" ); + } + l2x0_saved_regs.prefetch_ctrl = prefetch; }
Signature · 1 line
2.1.4
PATCH v3 1/1 ARM: l2c: add options to overwrite prefetching behavior
Will this make it into kernel 4.2 or do I have to do something so that this will make it into 4.2?
Hauke
Quoted 59 lines · Hauke Mehrtens
These options make it possible to overwrites the data and instruction prefetching behavior of the arm pl310 cache controller.
Signed-off-by Hauke Mehrtens <[email protected]>---
v2: only set prefetch
v1: set prefetch and auxDocumentation/devicetree/bindings/arm/l2cc.txt | 4 ++++ arch/arm/mm/cache-l2x0.c | 20 ++++++++++++++++++++ 2 files changed, 24 insertions(+)Documentation/devicetree/bindings/arm/l2cc.txt +4
-0@@ -67,6 +67,10 @@ Optional properties: disable if zero. - arm,prefetch-offset : Override prefetch offset value. Valid values are 0-7, 15, 23, and 31. +- arm,prefetch-data : Enable data prefetch. Enabling prefetching + can improve performance. +- arm,prefetch-instr : Enable instruction prefetch. Enabling prefetching + can improve performance. Example:arch/arm/mm/cache-l2x0.c +20
-0@@ -1199,6 +1199,26 @@ static void __init l2c310_of_parse(const struct device_node *np,pr_err ("L2C-310 OF arm,prefetch-offset property value is missing\n" ); } + ret =of_property_read_u32 (np,"arm,prefetch-data" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_DATA_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_DATA_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-data property value is missing\n" ); + } + + ret =of_property_read_u32 (np,"arm,prefetch-instr" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_INSTR_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_INSTR_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-instr property value is missing\n" ); + } + l2x0_saved_regs.prefetch_ctrl = prefetch; }
PATCH v3 1/1 ARM: l2c: add options to overwrite prefetching behavior
Quoted 2 lines · Hauke Mehrtens
Will this make it into kernel 4.2 or do I have to do something so that this will make it into 4.2?
I don't see anything wrong with it, but as ever, it needs to end up in the patch system if it's not going to get buried beneath a huge pile of email.
Thanks.
Quoted 63 lines
Hauke
Quoted 59 lines · Hauke Mehrtens
These options make it possible to overwrites the data and instruction prefetching behavior of the arm pl310 cache controller.
Signed-off-by Hauke Mehrtens <[email protected]>---
v2: only set prefetch
v1: set prefetch and auxDocumentation/devicetree/bindings/arm/l2cc.txt | 4 ++++ arch/arm/mm/cache-l2x0.c | 20 ++++++++++++++++++++ 2 files changed, 24 insertions(+)Documentation/devicetree/bindings/arm/l2cc.txt +4
-0@@ -67,6 +67,10 @@ Optional properties: disable if zero. - arm,prefetch-offset : Override prefetch offset value. Valid values are 0-7, 15, 23, and 31. +- arm,prefetch-data : Enable data prefetch. Enabling prefetching + can improve performance. +- arm,prefetch-instr : Enable instruction prefetch. Enabling prefetching + can improve performance. Example:arch/arm/mm/cache-l2x0.c +20
-0@@ -1199,6 +1199,26 @@ static void __init l2c310_of_parse(const struct device_node *np,pr_err ("L2C-310 OF arm,prefetch-offset property value is missing\n" ); } + ret =of_property_read_u32 (np,"arm,prefetch-data" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_DATA_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_DATA_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-data property value is missing\n" ); + } + + ret =of_property_read_u32 (np,"arm,prefetch-instr" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_INSTR_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_INSTR_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-instr property value is missing\n" ); + } + l2x0_saved_regs.prefetch_ctrl = prefetch; }
Signature · 2 lines
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up according to speedtest.net.
PATCH v3 1/1 ARM: l2c: add options to overwrite prefetching behavior
In reply to Hauke MehrtensQuoted 17 lines · Hauke Mehrtens
These options make it possible to overwrites the data and instruction prefetching behavior of the arm pl310 cache controller.
Signed-off-by Hauke Mehrtens <[email protected]>---
v2: only set prefetch
v1: set prefetch and auxDocumentation/devicetree/bindings/arm/l2cc.txt | 4 ++++ arch/arm/mm/cache-l2x0.c | 20 ++++++++++++++++++++ 2 files changed, 24 insertions(+)Documentation/devicetree/bindings/arm/l2cc.txt +0
-0
Documentation/devicetree/bindings/arm/l2cc.txt Optional properties: · line 71
Quoted 5 lines
Documentation/devicetree/bindings/arm/l2cc.txt +2
-0@@ -67,6 +67,10 @@ Optional properties: disable if zero. - arm,prefetch-offset : Override prefetch offset value. Valid values are 0-7, 15, 23, and 31. +- arm,prefetch-data : Enable data prefetch. Enabling prefetching + can improve performance.
I do not think the "can improve performance" has a place in a binding, this is either not technical enough about what this does, or marketing enough it does not buy us much.
data/instruction pre-fetching are commonly found on cache controller these days, so I would be tempted to remove the "arm," prefixing here since this can be generalized to other kinds of cache controllers. Documenting that this can be either a boolean, or accept a value (see below) could help.
Quoted 12 lines
Documentation/devicetree/bindings/arm/l2cc.txt +2
-0+- arm,prefetch-instr : Enable instruction prefetch. Enabling prefetching + can improve performance. Example:arch/arm/mm/cache-l2x0.c +0
-0@@ -1199,6 +1199,26 @@ static void __init l2c310_of_parse(const struct device_node *np,pr_err ("L2C-310 OF arm,prefetch-offset property value is missing\n" ); }
arch/arm/mm/cache-l2x0.c static void __init l2c310_of_parse(const struct device_node *np, · line 1210
Quoted 10 lines
arch/arm/mm/cache-l2x0.c +9
-0+ ret =of_property_read_u32 (np,"arm,prefetch-data" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_DATA_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_DATA_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-data property value is missing\n" ); + }
If we want to generalize the use of this property, there could indeed be a value associated with it, if the cache controller supports different pre-fetching strides, however this is not the cache for these cache controllers it seems, are not we going to show error messages more often than desired?
Signature · 1 line
Florian
PATCH v3 1/1 ARM: l2c: add options to overwrite prefetching behavior
Quoted 28 lines · Florian Fainelli
Quoted 17 lines · Hauke Mehrtens
These options make it possible to overwrites the data and instruction prefetching behavior of the arm pl310 cache controller.
Signed-off-by Hauke Mehrtens <[email protected]>---
v2: only set prefetch
v1: set prefetch and auxDocumentation/devicetree/bindings/arm/l2cc.txt | 4 ++++ arch/arm/mm/cache-l2x0.c | 20 ++++++++++++++++++++ 2 files changed, 24 insertions(+)Documentation/devicetree/bindings/arm/l2cc.txt +0
-0Documentation/devicetree/bindings/arm/l2cc.txt Optional properties: · line 71
Quoted 5 lines
Documentation/devicetree/bindings/arm/l2cc.txt +2
-0@@ -67,6 +67,10 @@ Optional properties: disable if zero. - arm,prefetch-offset : Override prefetch offset value. Valid values are 0-7, 15, 23, and 31. +- arm,prefetch-data : Enable data prefetch. Enabling prefetching + can improve performance.I do not think the "can improve performance" has a place in a binding, this is either not technical enough about what this does, or marketing enough it does not buy us much.
Quoted 5 lines
data/instruction pre-fetching are commonly found on cache controller these days, so I would be tempted to remove the "arm," prefixing here since this can be generalized to other kinds of cache controllers. Documenting that this can be either a boolean, or accept a value (see below) could help.
So you think I should only add prefetch-data and prefetch-instr without the arm prefix.
Quoted 14 lines
Quoted 14 lines
Documentation/devicetree/bindings/arm/l2cc.txt +2
-0+- arm,prefetch-instr : Enable instruction prefetch. Enabling prefetching + can improve performance. Example:arch/arm/mm/cache-l2x0.c +0
-0@@ -1199,6 +1199,26 @@ static void __init l2c310_of_parse(const struct device_node *np,pr_err ("L2C-310 OF arm,prefetch-offset property value is missing\n" ); }
Quoted 15 lines
arch/arm/mm/cache-l2x0.c static void __init l2c310_of_parse(const struct device_node *np, · line 1210
Quoted 9 lines
arch/arm/mm/cache-l2x0.c +9
-0+ ret =of_property_read_u32 (np,"arm,prefetch-data" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_DATA_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_DATA_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-data property value is missing\n" ); + }If we want to generalize the use of this property, there could indeed be a value associated with it, if the cache controller supports different pre-fetching strides, however this is not the cache for these cache controllers it seems, are not we going to show error messages more often than desired?
I did this so it is possible to deactivate the prefech mode. I do not know if somebody wants to do that. I haven't understood how you suggest I should change.
When you do not associate a value with an entry in device tree it is there or not there, so we could only activate it when it was not automatically detected, but we could not deactivate it, because the case when this value is not specified in device tree would be, use to auto detected the value.
Hauke
PATCH v3 1/1 ARM: l2c: add options to overwrite prefetching behavior
Quoted 31 lines · Hauke Mehrtens
Quoted 28 lines · Florian Fainelli
Quoted 17 lines · Hauke Mehrtens
These options make it possible to overwrites the data and instruction prefetching behavior of the arm pl310 cache controller.
Signed-off-by Hauke Mehrtens <[email protected]>---
v2: only set prefetch
v1: set prefetch and auxDocumentation/devicetree/bindings/arm/l2cc.txt | 4 ++++ arch/arm/mm/cache-l2x0.c | 20 ++++++++++++++++++++ 2 files changed, 24 insertions(+)Documentation/devicetree/bindings/arm/l2cc.txt +0
-0Documentation/devicetree/bindings/arm/l2cc.txt Optional properties: · line 71
Quoted 5 lines
Documentation/devicetree/bindings/arm/l2cc.txt +2
-0@@ -67,6 +67,10 @@ Optional properties: disable if zero. - arm,prefetch-offset : Override prefetch offset value. Valid values are 0-7, 15, 23, and 31. +- arm,prefetch-data : Enable data prefetch. Enabling prefetching + can improve performance.I do not think the "can improve performance" has a place in a binding, this is either not technical enough about what this does, or marketing enough it does not buy us much.
Quoted 8 lines
Quoted 5 lines
data/instruction pre-fetching are commonly found on cache controller these days, so I would be tempted to remove the "arm," prefixing here since this can be generalized to other kinds of cache controllers. Documenting that this can be either a boolean, or accept a value (see below) could help.
So you think I should only add prefetch-data and prefetch-instr without the arm prefix.
That's what I think yes, others may disagree.
Quoted 29 lines
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Documentation/devicetree/bindings/arm/l2cc.txt +2
-0+- arm,prefetch-instr : Enable instruction prefetch. Enabling prefetching + can improve performance. Example:arch/arm/mm/cache-l2x0.c +0
-0@@ -1199,6 +1199,26 @@ static void __init l2c310_of_parse(const struct device_node *np,pr_err ("L2C-310 OF arm,prefetch-offset property value is missing\n" ); }Quoted 15 lines
arch/arm/mm/cache-l2x0.c static void __init l2c310_of_parse(const struct device_node *np, · line 1210
Quoted 9 lines
arch/arm/mm/cache-l2x0.c +9
-0+ ret =of_property_read_u32 (np,"arm,prefetch-data" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_DATA_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_DATA_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-data property value is missing\n" ); + }If we want to generalize the use of this property, there could indeed be a value associated with it, if the cache controller supports different pre-fetching strides, however this is not the cache for these cache controllers it seems, are not we going to show error messages more often than desired?
Quoted 8 lines
I did this so it is possible to deactivate the prefech mode. I do not know if somebody wants to do that. I haven't understood how you suggest I should change.
When you do not associate a value with an entry in device tree it is there or not there, so we could only activate it when it was not automatically detected, but we could not deactivate it, because the case when this value is not specified in device tree would be, use to auto detected the value.
My point is that you use of_read_property_u32, but your example does not state what should be the value associated with this property in the binding, so it is unclear what are the results without looking at the code between these examples:
/* Enable data pre-fetching */
#1 arm,data-prefetch;
#2 arm,data-prefetch = <1>;
/* Disable data pre-fetching */
#3 arm,data-prefetch = <0>;
/* do nothing, empty aka retain existing settings set by firmware */ #4
Based on the code, only #2 and #3 are intended, which raises the question, do not we want of_read_property_bool() instead then? The binding does seem to suggest that only #1 and #4 are valid though.
Signature · 1 line
Florian
PATCH v3 1/1 ARM: l2c: add options to overwrite prefetching behavior
Quoted 93 lines · Florian Fainelli
Quoted 31 lines · Hauke Mehrtens
Quoted 28 lines · Florian Fainelli
Quoted 17 lines · Hauke Mehrtens
These options make it possible to overwrites the data and instruction prefetching behavior of the arm pl310 cache controller.
Signed-off-by Hauke Mehrtens <[email protected]>---
v2: only set prefetch
v1: set prefetch and auxDocumentation/devicetree/bindings/arm/l2cc.txt | 4 ++++ arch/arm/mm/cache-l2x0.c | 20 ++++++++++++++++++++ 2 files changed, 24 insertions(+)Documentation/devicetree/bindings/arm/l2cc.txt +0
-0Documentation/devicetree/bindings/arm/l2cc.txt Optional properties: · line 71
Quoted 5 lines
Documentation/devicetree/bindings/arm/l2cc.txt +2
-0@@ -67,6 +67,10 @@ Optional properties: disable if zero. - arm,prefetch-offset : Override prefetch offset value. Valid values are 0-7, 15, 23, and 31. +- arm,prefetch-data : Enable data prefetch. Enabling prefetching + can improve performance.I do not think the "can improve performance" has a place in a binding, this is either not technical enough about what this does, or marketing enough it does not buy us much.
Quoted 8 lines
Quoted 5 lines
data/instruction pre-fetching are commonly found on cache controller these days, so I would be tempted to remove the "arm," prefixing here since this can be generalized to other kinds of cache controllers. Documenting that this can be either a boolean, or accept a value (see below) could help.
So you think I should only add prefetch-data and prefetch-instr without the arm prefix.
That's what I think yes, others may disagree.
Quoted 29 lines
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Quoted 14 lines
Documentation/devicetree/bindings/arm/l2cc.txt +2
-0+- arm,prefetch-instr : Enable instruction prefetch. Enabling prefetching + can improve performance. Example:arch/arm/mm/cache-l2x0.c +0
-0@@ -1199,6 +1199,26 @@ static void __init l2c310_of_parse(const struct device_node *np,pr_err ("L2C-310 OF arm,prefetch-offset property value is missing\n" ); }Quoted 15 lines
arch/arm/mm/cache-l2x0.c static void __init l2c310_of_parse(const struct device_node *np, · line 1210
Quoted 9 lines
arch/arm/mm/cache-l2x0.c +9
-0+ ret =of_property_read_u32 (np,"arm,prefetch-data" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_DATA_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_DATA_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-data property value is missing\n" ); + }If we want to generalize the use of this property, there could indeed be a value associated with it, if the cache controller supports different pre-fetching strides, however this is not the cache for these cache controllers it seems, are not we going to show error messages more often than desired?
Quoted 8 lines
I did this so it is possible to deactivate the prefech mode. I do not know if somebody wants to do that. I haven't understood how you suggest I should change.
When you do not associate a value with an entry in device tree it is there or not there, so we could only activate it when it was not automatically detected, but we could not deactivate it, because the case when this value is not specified in device tree would be, use to auto detected the value.My point is that you use
of_read_property_u32, but your example does not state what should be the value associated with this property in the binding, so it is unclear what are the results without looking at the code between these examples:/* Enable data pre-fetching */
#1 arm,data-prefetch;
#2 arm,data-prefetch = <1>;/* Disable data pre-fetching */
#3 arm,data-prefetch = <0>;
Quoted 6 lines
/* do nothing, empty aka retain existing settings set by firmware */ #4
Based on the code, only #2 and #3 are intended, which raises the question, do not we want
of_read_property_bool()instead then? The binding does seem to suggest that only #1 and #4 are valid though.
I re-read the code, and I think if you just clarify the values in the binding to be: 0 (forcibly disable), 1 (forcibly enable), property absent (retain settings), this would be crystal clear.
Thanks!
Signature · 1 line
Florian
PATCH v3 1/1 ARM: l2c: add options to overwrite prefetching behavior
Quoted 39 lines · Florian Fainelli
Quoted 38 lines · Florian Fainelli
Quoted 37 lines · Hauke Mehrtens
Quoted 33 lines · Florian Fainelli
Quoted 17 lines · Hauke Mehrtens
These options make it possible to overwrites the data and instruction prefetching behavior of the arm pl310 cache controller.
Signed-off-by Hauke Mehrtens <[email protected]>---
v2: only set prefetch
v1: set prefetch and auxDocumentation/devicetree/bindings/arm/l2cc.txt | 4 ++++ arch/arm/mm/cache-l2x0.c | 20 ++++++++++++++++++++ 2 files changed, 24 insertions(+)Documentation/devicetree/bindings/arm/l2cc.txt +0
-0Documentation/devicetree/bindings/arm/l2cc.txt Optional properties: · line 71
Quoted 5 lines
Documentation/devicetree/bindings/arm/l2cc.txt +2
-0@@ -67,6 +67,10 @@ Optional properties: disable if zero. - arm,prefetch-offset : Override prefetch offset value. Valid values are 0-7, 15, 23, and 31. +- arm,prefetch-data : Enable data prefetch. Enabling prefetching + can improve performance.I do not think the "can improve performance" has a place in a binding, this is either not technical enough about what this does, or marketing enough it does not buy us much.
data/instruction pre-fetching are commonly found on cache controller these days, so I would be tempted to remove the "arm," prefixing here since this can be generalized to other kinds of cache controllers. Documenting that this can be either a boolean, or accept a value (see below) could help.
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So you think I should only add prefetch-data and prefetch-instr without the arm prefix.
That's what I think yes, others may disagree.
Are there any other opinions on this issue?
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Documentation/devicetree/bindings/arm/l2cc.txt +2
-0+- arm,prefetch-instr : Enable instruction prefetch. Enabling prefetching + can improve performance. Example:arch/arm/mm/cache-l2x0.c +0
-0@@ -1199,6 +1199,26 @@ static void __init l2c310_of_parse(const struct device_node *np,pr_err ("L2C-310 OF arm,prefetch-offset property value is missing\n" ); }Quoted 15 lines
arch/arm/mm/cache-l2x0.c static void __init l2c310_of_parse(const struct device_node *np, · line 1210
Quoted 9 lines
arch/arm/mm/cache-l2x0.c +9
-0+ ret =of_property_read_u32 (np,"arm,prefetch-data" , &val); +if (ret ==0 ) { +if (val) + prefetch |=L310_PREFETCH_CTRL_DATA_PREFETCH ; +else + prefetch &= ~L310_PREFETCH_CTRL_DATA_PREFETCH ; + }else if (ret != -EINVAL ) { +pr_err ("L2C-310 OF arm,prefetch-data property value is missing\n" ); + }If we want to generalize the use of this property, there could indeed be a value associated with it, if the cache controller supports different pre-fetching strides, however this is not the cache for these cache controllers it seems, are not we going to show error messages more often than desired?
Quoted 8 lines
I did this so it is possible to deactivate the prefech mode. I do not know if somebody wants to do that. I haven't understood how you suggest I should change.
When you do not associate a value with an entry in device tree it is there or not there, so we could only activate it when it was not automatically detected, but we could not deactivate it, because the case when this value is not specified in device tree would be, use to auto detected the value.My point is that you use
of_read_property_u32, but your example does not state what should be the value associated with this property in the binding, so it is unclear what are the results without looking at the code between these examples:/* Enable data pre-fetching */
#1 arm,data-prefetch;
#2 arm,data-prefetch = <1>;/* Disable data pre-fetching */
#3 arm,data-prefetch = <0>;/* do nothing, empty aka retain existing settings set by firmware */ #4
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Based on the code, only #2 and #3 are intended, which raises the question, do not we want
of_read_property_bool()instead then? The binding does seem to suggest that only #1 and #4 are valid though.I re-read the code, and I think if you just clarify the values in the binding to be: 0 (forcibly disable), 1 (forcibly enable), property absent (retain settings), this would be crystal clear.
Ok I will do that.
Hauke