[PATCH v1 1/2] ASoC: simple-card: Support custom DAI system clock IDs

[PATCH v1 1/2] ASoC: simple-card: Support custom DAI system clock IDs

[Aidan MacDonald]

Some DAIs have multiple system clock sources, which can be chosen
using the "clk_id" argument to snd_soc_dai_set_sysclk(). Currently
this is hardcoded to 0 when using simple cards, but that choice is
not always suitable.

Add the "system-clock-id" property to allow selecting a different
clock ID on a per-DAI basis.

To simplify the logic on DPCM cards, add a dummy "asoc_simple_dai"
instance and use that for the dummy components on DPCM links. This
ensures that when we're iterating over DAIs in the PCM runtime there
is always a matching "asoc_simple_dai" we can dereference.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
---
 include/sound/simple_card_utils.h     |  2 ++
 sound/soc/generic/simple-card-utils.c | 26 ++++++++++++++++++++------
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/include/sound/simple_card_utils.h b/include/sound/simple_card_utils.h
index a0b827f0c2f6..9f9a72299637 100644
--- a/include/sound/simple_card_utils.h
+++ b/include/sound/simple_card_utils.h
@@ -26,6 +26,7 @@ struct asoc_simple_dai {
 	const char *name;
 	unsigned int sysclk;
 	int clk_direction;
+	int sysclk_id;
 	int slots;
 	int slot_width;
 	unsigned int tx_slot_mask;
@@ -67,6 +68,7 @@ struct asoc_simple_priv {
 		struct prop_nums num;
 		unsigned int mclk_fs;
 	} *dai_props;
+	struct asoc_simple_dai dummy_dai;
 	struct asoc_simple_jack hp_jack;
 	struct asoc_simple_jack mic_jack;
 	struct snd_soc_dai_link *dai_link;
diff --git a/sound/soc/generic/simple-card-utils.c b/sound/soc/generic/simple-card-utils.c
index bef16833c487..d4d898e06e76 100644
--- a/sound/soc/generic/simple-card-utils.c
+++ b/sound/soc/generic/simple-card-utils.c
@@ -262,6 +262,9 @@ int asoc_simple_parse_clk(struct device *dev,
 	if (of_property_read_bool(node, "system-clock-direction-out"))
 		simple_dai->clk_direction = SND_SOC_CLOCK_OUT;
 
+	if (!of_property_read_u32(node, "system-clock-id", &val))
+		simple_dai->sysclk_id = val;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(asoc_simple_parse_clk);
@@ -355,7 +358,7 @@ void asoc_simple_shutdown(struct snd_pcm_substream *substream)
 
 		if (props->mclk_fs && !dai->clk_fixed && !snd_soc_dai_active(cpu_dai))
 			snd_soc_dai_set_sysclk(cpu_dai,
-					       0, 0, SND_SOC_CLOCK_OUT);
+					       dai->sysclk_id, 0, SND_SOC_CLOCK_OUT);
 
 		asoc_simple_clk_disable(dai);
 	}
@@ -364,7 +367,7 @@ void asoc_simple_shutdown(struct snd_pcm_substream *substream)
 
 		if (props->mclk_fs && !dai->clk_fixed && !snd_soc_dai_active(codec_dai))
 			snd_soc_dai_set_sysclk(codec_dai,
-					       0, 0, SND_SOC_CLOCK_IN);
+					       dai->sysclk_id, 0, SND_SOC_CLOCK_IN);
 
 		asoc_simple_clk_disable(dai);
 	}
@@ -439,7 +442,7 @@ int asoc_simple_hw_params(struct snd_pcm_substream *substream,
 	struct asoc_simple_priv *priv = snd_soc_card_get_drvdata(rtd->card);
 	struct simple_dai_props *props = simple_priv_to_props(priv, rtd->num);
 	unsigned int mclk, mclk_fs = 0;
-	int i, ret;
+	int i, ret, sysclk_id;
 
 	if (props->mclk_fs)
 		mclk_fs = props->mclk_fs;
@@ -472,13 +475,21 @@ int asoc_simple_hw_params(struct snd_pcm_substream *substream,
 		}
 
 		for_each_rtd_codec_dais(rtd, i, sdai) {
-			ret = snd_soc_dai_set_sysclk(sdai, 0, mclk, SND_SOC_CLOCK_IN);
+			pdai = simple_props_to_dai_codec(props, i);
+			sysclk_id = pdai->sysclk_id;
+
+			ret = snd_soc_dai_set_sysclk(sdai, sysclk_id, mclk,
+						     SND_SOC_CLOCK_IN);
 			if (ret && ret != -ENOTSUPP)
 				return ret;
 		}
 
 		for_each_rtd_cpu_dais(rtd, i, sdai) {
-			ret = snd_soc_dai_set_sysclk(sdai, 0, mclk, SND_SOC_CLOCK_OUT);
+			pdai = simple_props_to_dai_cpu(props, i);
+			sysclk_id = pdai->sysclk_id;
+
+			ret = snd_soc_dai_set_sysclk(sdai, pdai->sysclk_id, mclk,
+						     SND_SOC_CLOCK_OUT);
 			if (ret && ret != -ENOTSUPP)
 				return ret;
 		}
@@ -523,7 +534,8 @@ static int asoc_simple_init_dai(struct snd_soc_dai *dai,
 		return 0;
 
 	if (simple_dai->sysclk) {
-		ret = snd_soc_dai_set_sysclk(dai, 0, simple_dai->sysclk,
+		ret = snd_soc_dai_set_sysclk(dai, simple_dai->sysclk_id,
+					     simple_dai->sysclk,
 					     simple_dai->clk_direction);
 		if (ret && ret != -ENOTSUPP) {
 			dev_err(dai->dev, "simple-card: set_sysclk error\n");
@@ -858,6 +870,7 @@ int asoc_simple_init_priv(struct asoc_simple_priv *priv,
 			dai_link[i].cpus	= &priv->dummy;
 			dai_props[i].num.cpus	=
 			dai_link[i].num_cpus	= 1;
+			dai_props[i].cpu_dai	= &priv->dummy_dai;
 		}
 
 		if (li->num[i].codecs) {
@@ -882,6 +895,7 @@ int asoc_simple_init_priv(struct asoc_simple_priv *priv,
 			dai_link[i].codecs	= &priv->dummy;
 			dai_props[i].num.codecs	=
 			dai_link[i].num_codecs	= 1;
+			dai_props[i].codec_dai	= &priv->dummy_dai;
 		}
 
 		if (li->num[i].platforms) {
-- 
2.38.1

[PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Aidan MacDonald]

This is a new per-DAI property used to specify the clock ID argument
to snd_soc_dai_set_sysclk().

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
---
 Documentation/devicetree/bindings/sound/simple-card.yaml | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/sound/simple-card.yaml b/Documentation/devicetree/bindings/sound/simple-card.yaml
index ed19899bc94b..cb7774e235d0 100644
--- a/Documentation/devicetree/bindings/sound/simple-card.yaml
+++ b/Documentation/devicetree/bindings/sound/simple-card.yaml
@@ -57,6 +57,12 @@ definitions:
       single fixed sampling rate.
     $ref: /schemas/types.yaml#/definitions/flag
 
+  system-clock-id:
+    description: |
+      Specify the clock ID used for setting the DAI system clock.
+      Defaults to 0 if unspecified.
+    $ref: /schemas/types.yaml#/definitions/uint32
+
   mclk-fs:
     description: |
       Multiplication factor between stream rate and codec mclk.
@@ -145,6 +151,8 @@ definitions:
         $ref: "#/definitions/system-clock-direction-out"
       system-clock-fixed:
         $ref: "#/definitions/system-clock-fixed"
+      system-clock-id:
+        $ref: "#/definitions/system-clock-id"
     required:
       - sound-dai
 
-- 
2.38.1

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Krzysztof Kozlowski]

On 22/10/2022 12:27, Aidan MacDonald wrote:
> This is a new per-DAI property used to specify the clock ID argument
> to snd_soc_dai_set_sysclk().

You did no show the use of this property and here you refer to some
specific Linux driver implementation, so in total this does no look like
 a hardware property.

You also did not explain why do you need it (the most important piece of
commit msg).

> 
> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
> ---
>  Documentation/devicetree/bindings/sound/simple-card.yaml | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/sound/simple-card.yaml b/Documentation/devicetree/bindings/sound/simple-card.yaml
> index ed19899bc94b..cb7774e235d0 100644
> --- a/Documentation/devicetree/bindings/sound/simple-card.yaml
> +++ b/Documentation/devicetree/bindings/sound/simple-card.yaml
> @@ -57,6 +57,12 @@ definitions:
>        single fixed sampling rate.
>      $ref: /schemas/types.yaml#/definitions/flag
>  
> +  system-clock-id:
> +    description: |
> +      Specify the clock ID used for setting the DAI system clock.


With lack of explanation above, I would say - use common clock framework
to choose a clock...


Best regards,
Krzysztof

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Aidan MacDonald]

Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:

> On 22/10/2022 12:27, Aidan MacDonald wrote:
>> This is a new per-DAI property used to specify the clock ID argument
>> to snd_soc_dai_set_sysclk().
>
> You did no show the use of this property and here you refer to some
> specific Linux driver implementation, so in total this does no look like
>  a hardware property.
>
> You also did not explain why do you need it (the most important piece of
> commit msg).
>
>>
>> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
>> ---
>>  Documentation/devicetree/bindings/sound/simple-card.yaml | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/sound/simple-card.yaml b/Documentation/devicetree/bindings/sound/simple-card.yaml
>> index ed19899bc94b..cb7774e235d0 100644
>> --- a/Documentation/devicetree/bindings/sound/simple-card.yaml
>> +++ b/Documentation/devicetree/bindings/sound/simple-card.yaml
>> @@ -57,6 +57,12 @@ definitions:
>>        single fixed sampling rate.
>>      $ref: /schemas/types.yaml#/definitions/flag
>>
>> +  system-clock-id:
>> +    description: |
>> +      Specify the clock ID used for setting the DAI system clock.
>
>
> With lack of explanation above, I would say - use common clock framework
> to choose a clock...
>
>
> Best regards,
> Krzysztof

Sorry, I didn't explain things very well. The system clock ID is indeed
a property of the DAI hardware. The ID is not specific to Linux in any
way, and really it's an enumeration that requires a dt-binding.

A DAI may support multiple system clock inputs or outputs identified by
the clock ID. In the case of outputs, these could be distinct clocks
that have their own I/O pins, or the clock ID could select the internal
source clock used for a clock generator. For inputs, the system clock ID
may inform the DAI how or where the system clock is being provided so
hardware registers can be configured appropriately.

Really the details do not matter, except that in a particular DAI link
configuration a specific clock ID must be used. This is determined by
the actual hardware connection between the DAIs; if the wrong clock is
used, the DAI may not function correctly.

Currently the device tree is ambiguous as to which system clock should
be used when the DAI supports more than one, because there is no way to
specify which clock was intended. Linux just treats the ID as zero, but
that's currently a Linux-specific numbering so there's guarantee that
another OS would choose the same clock as Linux.

The system-clock-id property is therefore necessary to fully describe
the hardware connection between DAIs in a DAI link when a DAI offers
more than one choice of system clock.

I will resend the patch with the above in the commit message.

Regards,
Aidan

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Krzysztof Kozlowski]

On 23/10/2022 09:47, Aidan MacDonald wrote:
> 
> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:
> 
>> On 22/10/2022 12:27, Aidan MacDonald wrote:
>>> This is a new per-DAI property used to specify the clock ID argument
>>> to snd_soc_dai_set_sysclk().
>>
>> You did no show the use of this property and here you refer to some
>> specific Linux driver implementation, so in total this does no look like
>>  a hardware property.
>>
>> You also did not explain why do you need it (the most important piece of
>> commit msg).
>>
>>>
>>> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
>>> ---
>>>  Documentation/devicetree/bindings/sound/simple-card.yaml | 8 ++++++++
>>>  1 file changed, 8 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/sound/simple-card.yaml b/Documentation/devicetree/bindings/sound/simple-card.yaml
>>> index ed19899bc94b..cb7774e235d0 100644
>>> --- a/Documentation/devicetree/bindings/sound/simple-card.yaml
>>> +++ b/Documentation/devicetree/bindings/sound/simple-card.yaml
>>> @@ -57,6 +57,12 @@ definitions:
>>>        single fixed sampling rate.
>>>      $ref: /schemas/types.yaml#/definitions/flag
>>>
>>> +  system-clock-id:
>>> +    description: |
>>> +      Specify the clock ID used for setting the DAI system clock.
>>
>>
>> With lack of explanation above, I would say - use common clock framework
>> to choose a clock...
>>
>>
>> Best regards,
>> Krzysztof
> 
> Sorry, I didn't explain things very well. The system clock ID is indeed
> a property of the DAI hardware. The ID is not specific to Linux in any
> way, and really it's an enumeration that requires a dt-binding.
> 
> A DAI may support multiple system clock inputs or outputs identified by
> the clock ID. In the case of outputs, these could be distinct clocks
> that have their own I/O pins, or the clock ID could select the internal
> source clock used for a clock generator. For inputs, the system clock ID
> may inform the DAI how or where the system clock is being provided so
> hardware registers can be configured appropriately.
> 
> Really the details do not matter, except that in a particular DAI link
> configuration a specific clock ID must be used. This is determined by
> the actual hardware connection between the DAIs; if the wrong clock is
> used, the DAI may not function correctly.
> 
> Currently the device tree is ambiguous as to which system clock should
> be used when the DAI supports more than one, because there is no way to
> specify which clock was intended. Linux just treats the ID as zero, but
> that's currently a Linux-specific numbering so there's guarantee that
> another OS would choose the same clock as Linux.
> 
> The system-clock-id property is therefore necessary to fully describe
> the hardware connection between DAIs in a DAI link when a DAI offers
> more than one choice of system clock.
> 
> I will resend the patch with the above in the commit message.

For example if you want to define which input pin to use (so you have
internal mux), it's quite unspecific to give them some indexes. What is
0? What is 1? Number of pin? Number of pin counting from where?

Since this is unanswered, the IDs are also driver and implementation
dependent, thus you still have the same problem - another OS can choose
different clock. That's not then a hardware description, but software
configuration.

Best regards,
Krzysztof

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Aidan MacDonald]

Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:

> On 23/10/2022 09:47, Aidan MacDonald wrote:
>>
>> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:
>>
>>> On 22/10/2022 12:27, Aidan MacDonald wrote:
>>>> This is a new per-DAI property used to specify the clock ID argument
>>>> to snd_soc_dai_set_sysclk().
>>>
>>> You did no show the use of this property and here you refer to some
>>> specific Linux driver implementation, so in total this does no look like
>>>  a hardware property.
>>>
>>> You also did not explain why do you need it (the most important piece of
>>> commit msg).
>>>
>>>>
>>>> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
>>>> ---
>>>>  Documentation/devicetree/bindings/sound/simple-card.yaml | 8 ++++++++
>>>>  1 file changed, 8 insertions(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/sound/simple-card.yaml b/Documentation/devicetree/bindings/sound/simple-card.yaml
>>>> index ed19899bc94b..cb7774e235d0 100644
>>>> --- a/Documentation/devicetree/bindings/sound/simple-card.yaml
>>>> +++ b/Documentation/devicetree/bindings/sound/simple-card.yaml
>>>> @@ -57,6 +57,12 @@ definitions:
>>>>        single fixed sampling rate.
>>>>      $ref: /schemas/types.yaml#/definitions/flag
>>>>
>>>> +  system-clock-id:
>>>> +    description: |
>>>> +      Specify the clock ID used for setting the DAI system clock.
>>>
>>>
>>> With lack of explanation above, I would say - use common clock framework
>>> to choose a clock...
>>>
>>>
>>> Best regards,
>>> Krzysztof
>>
>> Sorry, I didn't explain things very well. The system clock ID is indeed
>> a property of the DAI hardware. The ID is not specific to Linux in any
>> way, and really it's an enumeration that requires a dt-binding.
>>
>> A DAI may support multiple system clock inputs or outputs identified by
>> the clock ID. In the case of outputs, these could be distinct clocks
>> that have their own I/O pins, or the clock ID could select the internal
>> source clock used for a clock generator. For inputs, the system clock ID
>> may inform the DAI how or where the system clock is being provided so
>> hardware registers can be configured appropriately.
>>
>> Really the details do not matter, except that in a particular DAI link
>> configuration a specific clock ID must be used. This is determined by
>> the actual hardware connection between the DAIs; if the wrong clock is
>> used, the DAI may not function correctly.
>>
>> Currently the device tree is ambiguous as to which system clock should
>> be used when the DAI supports more than one, because there is no way to
>> specify which clock was intended. Linux just treats the ID as zero, but
>> that's currently a Linux-specific numbering so there's guarantee that
>> another OS would choose the same clock as Linux.
>>
>> The system-clock-id property is therefore necessary to fully describe
>> the hardware connection between DAIs in a DAI link when a DAI offers
>> more than one choice of system clock.
>>
>> I will resend the patch with the above in the commit message.
>
> For example if you want to define which input pin to use (so you have
> internal mux), it's quite unspecific to give them some indexes. What is
> 0? What is 1? Number of pin? Number of pin counting from where?
>
> Since this is unanswered, the IDs are also driver and implementation
> dependent, thus you still have the same problem - another OS can choose
> different clock. That's not then a hardware description, but software
> configuration.
>
> Best regards,
> Krzysztof

I answered this already. The enumeration is arbitrary. Create some
dt-bindings and voila, it becomes standardized and OS-independent.

Regards,
Aidan

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Krzysztof Kozlowski]

On 24/10/2022 19:38, Aidan MacDonald wrote:
> 
> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:
> 
>> On 23/10/2022 09:47, Aidan MacDonald wrote:
>>>
>>> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:
>>>
>>>> On 22/10/2022 12:27, Aidan MacDonald wrote:
>>>>> This is a new per-DAI property used to specify the clock ID argument
>>>>> to snd_soc_dai_set_sysclk().
>>>>
>>>> You did no show the use of this property and here you refer to some
>>>> specific Linux driver implementation, so in total this does no look like
>>>>  a hardware property.
>>>>
>>>> You also did not explain why do you need it (the most important piece of
>>>> commit msg).
>>>>
>>>>>
>>>>> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
>>>>> ---
>>>>>  Documentation/devicetree/bindings/sound/simple-card.yaml | 8 ++++++++
>>>>>  1 file changed, 8 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/sound/simple-card.yaml b/Documentation/devicetree/bindings/sound/simple-card.yaml
>>>>> index ed19899bc94b..cb7774e235d0 100644
>>>>> --- a/Documentation/devicetree/bindings/sound/simple-card.yaml
>>>>> +++ b/Documentation/devicetree/bindings/sound/simple-card.yaml
>>>>> @@ -57,6 +57,12 @@ definitions:
>>>>>        single fixed sampling rate.
>>>>>      $ref: /schemas/types.yaml#/definitions/flag
>>>>>
>>>>> +  system-clock-id:
>>>>> +    description: |
>>>>> +      Specify the clock ID used for setting the DAI system clock.
>>>>
>>>>
>>>> With lack of explanation above, I would say - use common clock framework
>>>> to choose a clock...
>>>>
>>>>
>>>> Best regards,
>>>> Krzysztof
>>>
>>> Sorry, I didn't explain things very well. The system clock ID is indeed
>>> a property of the DAI hardware. The ID is not specific to Linux in any
>>> way, and really it's an enumeration that requires a dt-binding.
>>>
>>> A DAI may support multiple system clock inputs or outputs identified by
>>> the clock ID. In the case of outputs, these could be distinct clocks
>>> that have their own I/O pins, or the clock ID could select the internal
>>> source clock used for a clock generator. For inputs, the system clock ID
>>> may inform the DAI how or where the system clock is being provided so
>>> hardware registers can be configured appropriately.
>>>
>>> Really the details do not matter, except that in a particular DAI link
>>> configuration a specific clock ID must be used. This is determined by
>>> the actual hardware connection between the DAIs; if the wrong clock is
>>> used, the DAI may not function correctly.
>>>
>>> Currently the device tree is ambiguous as to which system clock should
>>> be used when the DAI supports more than one, because there is no way to
>>> specify which clock was intended. Linux just treats the ID as zero, but
>>> that's currently a Linux-specific numbering so there's guarantee that
>>> another OS would choose the same clock as Linux.
>>>
>>> The system-clock-id property is therefore necessary to fully describe
>>> the hardware connection between DAIs in a DAI link when a DAI offers
>>> more than one choice of system clock.
>>>
>>> I will resend the patch with the above in the commit message.
>>
>> For example if you want to define which input pin to use (so you have
>> internal mux), it's quite unspecific to give them some indexes. What is
>> 0? What is 1? Number of pin? Number of pin counting from where?
>>
>> Since this is unanswered, the IDs are also driver and implementation
>> dependent, thus you still have the same problem - another OS can choose
>> different clock. That's not then a hardware description, but software
>> configuration.
>>
>> Best regards,
>> Krzysztof
> 
> I answered this already. The enumeration is arbitrary. Create some
> dt-bindings and voila, it becomes standardized and OS-independent.

Hm, then I missed something. Can you point me to DTS and bindings
(patches or in-tree) which show this standardized indices of clock inputs?

Best regards,
Krzysztof

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Aidan MacDonald]

Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:

> On 24/10/2022 19:38, Aidan MacDonald wrote:
>>
>> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:
>>
>>> On 23/10/2022 09:47, Aidan MacDonald wrote:
>>>>
>>>> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:
>>>>
>>>>> On 22/10/2022 12:27, Aidan MacDonald wrote:
>>>>>> This is a new per-DAI property used to specify the clock ID argument
>>>>>> to snd_soc_dai_set_sysclk().
>>>>>
>>>>> You did no show the use of this property and here you refer to some
>>>>> specific Linux driver implementation, so in total this does no look like
>>>>>  a hardware property.
>>>>>
>>>>> You also did not explain why do you need it (the most important piece of
>>>>> commit msg).
>>>>>
>>>>>>
>>>>>> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
>>>>>> ---
>>>>>>  Documentation/devicetree/bindings/sound/simple-card.yaml | 8 ++++++++
>>>>>>  1 file changed, 8 insertions(+)
>>>>>>
>>>>>> diff --git a/Documentation/devicetree/bindings/sound/simple-card.yaml b/Documentation/devicetree/bindings/sound/simple-card.yaml
>>>>>> index ed19899bc94b..cb7774e235d0 100644
>>>>>> --- a/Documentation/devicetree/bindings/sound/simple-card.yaml
>>>>>> +++ b/Documentation/devicetree/bindings/sound/simple-card.yaml
>>>>>> @@ -57,6 +57,12 @@ definitions:
>>>>>>        single fixed sampling rate.
>>>>>>      $ref: /schemas/types.yaml#/definitions/flag
>>>>>>
>>>>>> +  system-clock-id:
>>>>>> +    description: |
>>>>>> +      Specify the clock ID used for setting the DAI system clock.
>>>>>
>>>>>
>>>>> With lack of explanation above, I would say - use common clock framework
>>>>> to choose a clock...
>>>>>
>>>>>
>>>>> Best regards,
>>>>> Krzysztof
>>>>
>>>> Sorry, I didn't explain things very well. The system clock ID is indeed
>>>> a property of the DAI hardware. The ID is not specific to Linux in any
>>>> way, and really it's an enumeration that requires a dt-binding.
>>>>
>>>> A DAI may support multiple system clock inputs or outputs identified by
>>>> the clock ID. In the case of outputs, these could be distinct clocks
>>>> that have their own I/O pins, or the clock ID could select the internal
>>>> source clock used for a clock generator. For inputs, the system clock ID
>>>> may inform the DAI how or where the system clock is being provided so
>>>> hardware registers can be configured appropriately.
>>>>
>>>> Really the details do not matter, except that in a particular DAI link
>>>> configuration a specific clock ID must be used. This is determined by
>>>> the actual hardware connection between the DAIs; if the wrong clock is
>>>> used, the DAI may not function correctly.
>>>>
>>>> Currently the device tree is ambiguous as to which system clock should
>>>> be used when the DAI supports more than one, because there is no way to
>>>> specify which clock was intended. Linux just treats the ID as zero, but
>>>> that's currently a Linux-specific numbering so there's guarantee that
>>>> another OS would choose the same clock as Linux.
>>>>
>>>> The system-clock-id property is therefore necessary to fully describe
>>>> the hardware connection between DAIs in a DAI link when a DAI offers
>>>> more than one choice of system clock.
>>>>
>>>> I will resend the patch with the above in the commit message.
>>>
>>> For example if you want to define which input pin to use (so you have
>>> internal mux), it's quite unspecific to give them some indexes. What is
>>> 0? What is 1? Number of pin? Number of pin counting from where?
>>>
>>> Since this is unanswered, the IDs are also driver and implementation
>>> dependent, thus you still have the same problem - another OS can choose
>>> different clock. That's not then a hardware description, but software
>>> configuration.
>>>
>>> Best regards,
>>> Krzysztof
>>
>> I answered this already. The enumeration is arbitrary. Create some
>> dt-bindings and voila, it becomes standardized and OS-independent.
>
> Hm, then I missed something. Can you point me to DTS and bindings
> (patches or in-tree) which show this standardized indices of clock inputs?
>
> Best regards,
> Krzysztof

Device trees already use standardized enumerations in other areas so it
isn't a new idea. Look under include/dt-bindings/clock. Every header
there contains an arbitrary enumeration of a device's clocks. In fact
most of include/dt-bindings is exactly for this purpose, to define
standard values that are not "just numbers" but an enum, a flag, etc,
with a special meaning. It is not specific to clocks.

There is no dt-binding for system clock ID, because prior to this patch
they were not exposed to DT in any way. But the enumerations themselves
already exist, eg. the IDs for nau8821 codec:

    /* System Clock Source */
    enum {
        NAU8821_CLK_DIS,
        NAU8821_CLK_MCLK,
        NAU8821_CLK_INTERNAL,
        NAU8821_CLK_FLL_MCLK,
        NAU8821_CLK_FLL_BLK,
        NAU8821_CLK_FLL_FS,
    };

We would just be moving these into dt-bindings if somebody wants to
use a codec with simple-card. Future drivers would add the enum into
dt-bindings from the start because that's where it belongs.

Regards,
Aidan

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Krzysztof Kozlowski]

On 25/10/2022 05:14, Aidan MacDonald wrote:
>> Krzysztof
> 
> Device trees already use standardized enumerations in other areas so it
> isn't a new idea. Look under include/dt-bindings/clock. Every header
> there contains an arbitrary enumeration of a device's clocks. In fact
> most of include/dt-bindings is exactly for this purpose, to define
> standard values that are not "just numbers" but an enum, a flag, etc,
> with a special meaning. It is not specific to clocks.
> 
> There is no dt-binding for system clock ID, because prior to this patch
> they were not exposed to DT in any way. But the enumerations themselves
> already exist, eg. the IDs for nau8821 codec:
> 
>     /* System Clock Source */
>     enum {
>         NAU8821_CLK_DIS,
>         NAU8821_CLK_MCLK,
>         NAU8821_CLK_INTERNAL,
>         NAU8821_CLK_FLL_MCLK,
>         NAU8821_CLK_FLL_BLK,
>         NAU8821_CLK_FLL_FS,
>     };

OK, this looks good.

> 
> We would just be moving these into dt-bindings if somebody wants to
> use a codec with simple-card. Future drivers would add the enum into
> dt-bindings from the start because that's where it belongs.

And the remaining piece I don't get is that these are not bindings for
codec, but for sound audio card. You want to set "system-clock-id"
property for audio card, while putting clock from codec, which will be
used to pass back to the codec... so it is a property of the codec, not
of the audio card. IOW, NAU8821_CLK_* does not configure here the clock
of the system, but only, only clock of the codec.



Best regards,
Krzysztof

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Aidan MacDonald]

Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:

> And the remaining piece I don't get is that these are not bindings for
> codec, but for sound audio card. You want to set "system-clock-id"
> property for audio card, while putting clock from codec, which will be
> used to pass back to the codec... so it is a property of the codec, not
> of the audio card. IOW, NAU8821_CLK_* does not configure here the clock
> of the system, but only, only clock of the codec.

The system clock is controlled at the DAI level, it's specific to one
DAI on one component. The simple-card device node has sub-nodes for the
DAI links, and each DAI link node has sub-nodes for the DAIs within the
link. "system-clock-id" is a property on the DAI nodes, so it's not a
card-level property, just one part of the overall card definition.

Since the clock ID is something defined by the codec it would naturally
be a value defined by the codec, but the *configuration* of the codec is
part of the sound card because it depends on how everything is connected
together. If you used the same codec in a different machine it would
have a different configuration.

Regards,
Aidan

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Krzysztof Kozlowski]

On 26/10/2022 10:48, Aidan MacDonald wrote:
> 
> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:
> 
>> And the remaining piece I don't get is that these are not bindings for
>> codec, but for sound audio card. You want to set "system-clock-id"
>> property for audio card, while putting clock from codec, which will be
>> used to pass back to the codec... so it is a property of the codec, not
>> of the audio card. IOW, NAU8821_CLK_* does not configure here the clock
>> of the system, but only, only clock of the codec.
> 
> The system clock is controlled at the DAI level, it's specific to one
> DAI on one component. The simple-card device node has sub-nodes for the
> DAI links, and each DAI link node has sub-nodes for the DAIs within the
> link. "system-clock-id" is a property on the DAI nodes, so it's not a
> card-level property, just one part of the overall card definition.
> 
> Since the clock ID is something defined by the codec it would naturally
> be a value defined by the codec, but the *configuration* of the codec is
> part of the sound card because it depends on how everything is connected
> together. If you used the same codec in a different machine it would
> have a different configuration.


OK, that sounds reasonable. Thank you for explaining this. You still
need to convince Mark :)

Best regards,
Krzysztof

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Aidan MacDonald]

Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:

> On 26/10/2022 10:48, Aidan MacDonald wrote:
>>
>> Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> writes:
>>
>>> And the remaining piece I don't get is that these are not bindings for
>>> codec, but for sound audio card. You want to set "system-clock-id"
>>> property for audio card, while putting clock from codec, which will be
>>> used to pass back to the codec... so it is a property of the codec, not
>>> of the audio card. IOW, NAU8821_CLK_* does not configure here the clock
>>> of the system, but only, only clock of the codec.
>>
>> The system clock is controlled at the DAI level, it's specific to one
>> DAI on one component. The simple-card device node has sub-nodes for the
>> DAI links, and each DAI link node has sub-nodes for the DAIs within the
>> link. "system-clock-id" is a property on the DAI nodes, so it's not a
>> card-level property, just one part of the overall card definition.
>>
>> Since the clock ID is something defined by the codec it would naturally
>> be a value defined by the codec, but the *configuration* of the codec is
>> part of the sound card because it depends on how everything is connected
>> together. If you used the same codec in a different machine it would
>> have a different configuration.
>
> OK, that sounds reasonable. Thank you for explaining this. You still
> need to convince Mark :)

No problem, thanks for bearing with all my explanations! Mark raised
some good points, and I have to agree with him. This could create too
many future issues, and the problem might be better solved with the
clock API -- but unfortunately that's not yet feasible.

Regards,
Aidan

Re: [PATCH v1 2/2] dt-bindings: ASoC: simple-card: Add system-clock-id property

[Krzysztof Kozlowski]

On 22/10/2022 12:27, Aidan MacDonald wrote:
> This is a new per-DAI property used to specify the clock ID argument
> to snd_soc_dai_set_sysclk().
> 
> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
> ---
>  Documentation/devicetree/bindings/sound/simple-card.yaml | 8 ++++++++
>  1 file changed, 8 insertions(+)

My concerns were addressed, so:

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof

Re: [PATCH v1 1/2] ASoC: simple-card: Support custom DAI system clock IDs

[Kuninori Morimoto]

Hi Aidan

Thank you for your patch

> Some DAIs have multiple system clock sources, which can be chosen
> using the "clk_id" argument to snd_soc_dai_set_sysclk(). Currently
> this is hardcoded to 0 when using simple cards, but that choice is
> not always suitable.
> 
> Add the "system-clock-id" property to allow selecting a different
> clock ID on a per-DAI basis.
> 
> To simplify the logic on DPCM cards, add a dummy "asoc_simple_dai"
> instance and use that for the dummy components on DPCM links. This
> ensures that when we're iterating over DAIs in the PCM runtime there
> is always a matching "asoc_simple_dai" we can dereference.
> 
> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
> ---

I think adding "system-clock-id" and adding "dummy asoc_simple_dai" are
different topics. This patch should be separated into 2 patches.

And I couldn't understand the reason why we need to add dummy asoc_simple_dai.
In my understanding, we don't parse DT for dummy connection.
Which process are you talking about specifically here?

	This ensures that when we're iterating over DAIs in the PCM runtime there
	is always a matching "asoc_simple_dai" we can dereference.
- 
Thank you for your help !!

Best regards
---
Kuninori Morimoto

Re: [PATCH v1 1/2] ASoC: simple-card: Support custom DAI system clock IDs

[Aidan MacDonald]

Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> writes:

> Hi Aidan
>
> Thank you for your patch
>
>> Some DAIs have multiple system clock sources, which can be chosen
>> using the "clk_id" argument to snd_soc_dai_set_sysclk(). Currently
>> this is hardcoded to 0 when using simple cards, but that choice is
>> not always suitable.
>>
>> Add the "system-clock-id" property to allow selecting a different
>> clock ID on a per-DAI basis.
>>
>> To simplify the logic on DPCM cards, add a dummy "asoc_simple_dai"
>> instance and use that for the dummy components on DPCM links. This
>> ensures that when we're iterating over DAIs in the PCM runtime there
>> is always a matching "asoc_simple_dai" we can dereference.
>>
>> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
>> ---
>
> I think adding "system-clock-id" and adding "dummy asoc_simple_dai" are
> different topics. This patch should be separated into 2 patches.

Sounds good to me.

> And I couldn't understand the reason why we need to add dummy asoc_simple_dai.
> In my understanding, we don't parse DT for dummy connection.
> Which process are you talking about specifically here?
>
> 	This ensures that when we're iterating over DAIs in the PCM runtime there
> 	is always a matching "asoc_simple_dai" we can dereference.
> -
> Thank you for your help !!
>
> Best regards
> ---
> Kuninori Morimoto

DPCM DAI links have some real DAIs and one dummy DAI. Each real DAI has
an asoc_simple_dai associated with it to contain the information parsed
from the DT. The dummy DAI does not have an asoc_simple_dai. I'm adding
a dummy asoc_simple_dai for these dummy DAIs to make the mapping of
snd_soc_dai to asoc_simple_dai 1-to-1.

The non 1-to-1 mapping is problematic, because if I have a snd_soc_dai
and want to look up a simple-card property I would need to check if the
matching asoc_simple_dai exists first, and have a special case for DPCM
dummy DAIs. With a 1-to-1 mapping I can handle all DAIs the same way.

Regards,
Aidan

Re: [PATCH v1 1/2] ASoC: simple-card: Support custom DAI system clock IDs

[Mark Brown]

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On Sat, Oct 22, 2022 at 05:27:41PM +0100, Aidan MacDonald wrote:

> Some DAIs have multiple system clock sources, which can be chosen
> using the "clk_id" argument to snd_soc_dai_set_sysclk(). Currently
> this is hardcoded to 0 when using simple cards, but that choice is
> not always suitable.

We already have clock bindings, if we need to configure clocks we should
be using those to configure there.

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Re: [PATCH v1 1/2] ASoC: simple-card: Support custom DAI system clock IDs

[Aidan MacDonald]

Mark Brown <broonie@kernel.org> writes:

> On Sat, Oct 22, 2022 at 05:27:41PM +0100, Aidan MacDonald wrote:
>
>> Some DAIs have multiple system clock sources, which can be chosen
>> using the "clk_id" argument to snd_soc_dai_set_sysclk(). Currently
>> this is hardcoded to 0 when using simple cards, but that choice is
>> not always suitable.
>
> We already have clock bindings, if we need to configure clocks we should
> be using those to configure there.

The existing clock bindings are only useful for setting rates, and
.set_sysclk() does more than that. See my reply to Krzysztof if you
want an explanation, check nau8821 or tas2552 codecs for an example
of the kind of thing I'm talking about.

I picked those codecs at random, but they are fairly representative:
often a codec will allow the system clock to be derived from another
I2S clock (eg. BCLK), or provided directly, or maybe generated from an
internal PLL. In cases like that you need to configure the codec with
.set_sysclk() to select the right input. Many card drivers need to do
this, it's just as important as .set_fmt() or .hw_params().

Normal DT clocks don't seem capable of doing the job of .set_sysclk()
even in principle.

Regards,
Aidan

Re: [PATCH v1 1/2] ASoC: simple-card: Support custom DAI system clock IDs

[Mark Brown]

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On Tue, Oct 25, 2022 at 12:17:25AM +0100, Aidan MacDonald wrote:
> Mark Brown <broonie@kernel.org> writes:

> > We already have clock bindings, if we need to configure clocks we should
> > be using those to configure there.

> The existing clock bindings are only useful for setting rates, and
> .set_sysclk() does more than that. See my reply to Krzysztof if you
> want an explanation, check nau8821 or tas2552 codecs for an example
> of the kind of thing I'm talking about.

I thought there was stuff for muxes, but in any case if you are adding a
new binding here you could just as well add one to the clock bindings.

> I picked those codecs at random, but they are fairly representative:
> often a codec will allow the system clock to be derived from another
> I2S clock (eg. BCLK), or provided directly, or maybe generated from an
> internal PLL. In cases like that you need to configure the codec with
> .set_sysclk() to select the right input. Many card drivers need to do
> this, it's just as important as .set_fmt() or .hw_params().

There is a strong case for saying that all the clocking in CODECs might
fit into the clock API, especially given the whole DT thing.

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Re: [PATCH v1 1/2] ASoC: simple-card: Support custom DAI system clock IDs

[Aidan MacDonald]

Mark Brown <broonie@kernel.org> writes:

> On Tue, Oct 25, 2022 at 12:17:25AM +0100, Aidan MacDonald wrote:
>> Mark Brown <broonie@kernel.org> writes:
>
>> > We already have clock bindings, if we need to configure clocks we should
>> > be using those to configure there.
>
>> The existing clock bindings are only useful for setting rates, and
>> .set_sysclk() does more than that. See my reply to Krzysztof if you
>> want an explanation, check nau8821 or tas2552 codecs for an example
>> of the kind of thing I'm talking about.
>
> I thought there was stuff for muxes, but in any case if you are adding a
> new binding here you could just as well add one to the clock bindings.
>
>> I picked those codecs at random, but they are fairly representative:
>> often a codec will allow the system clock to be derived from another
>> I2S clock (eg. BCLK), or provided directly, or maybe generated from an
>> internal PLL. In cases like that you need to configure the codec with
>> .set_sysclk() to select the right input. Many card drivers need to do
>> this, it's just as important as .set_fmt() or .hw_params().
>
> There is a strong case for saying that all the clocking in CODECs might
> fit into the clock API, especially given the whole DT thing.

The ASoC APIs don't speak "struct clk", which seems (to me) like a
prerequisite before we can think about doing anything with clocks.

Even if ASoC began to use the clock API for codec clocking, it's not
clear how you maintain backward compatibility with the existing
simple-card bindings. You'd have to go over all DAIs and mimic the
effects of "snd_soc_dai_set_sysclk(dai, 0, freq, dir)" because there
could be a device tree relying on it somewhere.

So... given you're already stuck maintaining .set_sysclk() behavior
forever, is there much harm in exposing the sysclock ID to the DT?

Re: [PATCH v1 1/2] ASoC: simple-card: Support custom DAI system clock IDs

[Mark Brown]

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On Wed, Oct 26, 2022 at 03:42:31PM +0100, Aidan MacDonald wrote:
> Mark Brown <broonie@kernel.org> writes:

> > There is a strong case for saying that all the clocking in CODECs might
> > fit into the clock API, especially given the whole DT thing.

> The ASoC APIs don't speak "struct clk", which seems (to me) like a
> prerequisite before we can think about doing anything with clocks.

Right, they probably should.

> Even if ASoC began to use the clock API for codec clocking, it's not
> clear how you maintain backward compatibility with the existing
> simple-card bindings. You'd have to go over all DAIs and mimic the
> effects of "snd_soc_dai_set_sysclk(dai, 0, freq, dir)" because there
> could be a device tree relying on it somewhere.

Of course, you'd need to define bindings for devices with multiple
clocks such that things continue to work out compatibly.

> So... given you're already stuck maintaining .set_sysclk() behavior
> forever, is there much harm in exposing the sysclock ID to the DT?

Yes, it's ABI and the more baked in this stuff gets the more issues we
have when trying to integrate with the wider clock tree in the system -
for example when devices are able to output their system clock to be
used as a master clock for a device which can use the clock API as an
input.  It's fine in kernel but we should be trying to keep it out of
ABI.

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Re: [PATCH v1 1/2] ASoC: simple-card: Support custom DAI system clock IDs

[Aidan MacDonald]

Mark Brown <broonie@kernel.org> writes:

> On Wed, Oct 26, 2022 at 03:42:31PM +0100, Aidan MacDonald wrote:
>> Mark Brown <broonie@kernel.org> writes:
>>
>>> There is a strong case for saying that all the clocking in CODECs might
>>> fit into the clock API, especially given the whole DT thing.
>>>
>> The ASoC APIs don't speak "struct clk", which seems (to me) like a
>> prerequisite before we can think about doing anything with clocks.
>
> Right, they probably should.

Let me throw out an idea then... the clock API will probably need to
gain the ability to express constraints, eg. limit a clock to set of
frequencies or frequency ranges; ratio constraints to ensure a set of
clocks are in one of a specified set of ratios; and maybe require that
certain clocks be synchronous.

This'd go a long way toward making the clock API suitable for audio
clocking.

>> Even if ASoC began to use the clock API for codec clocking, it's not
>> clear how you maintain backward compatibility with the existing
>> simple-card bindings. You'd have to go over all DAIs and mimic the
>> effects of "snd_soc_dai_set_sysclk(dai, 0, freq, dir)" because there
>> could be a device tree relying on it somewhere.
>
> Of course, you'd need to define bindings for devices with multiple
> clocks such that things continue to work out compatibly.
>
>> So... given you're already stuck maintaining .set_sysclk() behavior
>> forever, is there much harm in exposing the sysclock ID to the DT?
>
> Yes, it's ABI and the more baked in this stuff gets the more issues we
> have when trying to integrate with the wider clock tree in the system -
> for example when devices are able to output their system clock to be
> used as a master clock for a device which can use the clock API as an
> input.  It's fine in kernel but we should be trying to keep it out of
> ABI.

Fair enough. It's too bad this limits the usefulness of simple-card,
but for the time being I'm happy maintaining these patches out of tree.

Regards,
Aidan