Re: [RESEND PATCH v2 1/2] ASoC: stm32: add bindings for SAI

Re: [RESEND PATCH v2 1/2] ASoC: stm32: add bindings for SAI

[Olivier MOYSAN]

Hello Rob,

On 03/18/2017 09:43 PM, Rob Herring wrote:
> On Thu, Mar 16, 2017 at 5:50 AM, Olivier MOYSAN <olivier.moysan@st.com> wrote:
>> Hello Rob,
>>
>> Thanks for your feedback.
>>
>> On 03/15/2017 06:46 PM, Rob Herring wrote:
>>> On Tue, Mar 07, 2017 at 10:44:31AM +0100, olivier moysan wrote:
>>>> This patch adds documentation of device tree bindings for the
>>>> STM32 SAI ASoC driver.
>>>>
>>>> Signed-off-by: olivier moysan <olivier.moysan@st.com>
>>>> ---
>>>>  .../devicetree/bindings/sound/st,stm32-sai.txt     | 79 ++++++++++++++++++++++
>>>>  1 file changed, 79 insertions(+)
>>>>  create mode 100644 Documentation/devicetree/bindings/sound/st,stm32-sai.txt
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/sound/st,stm32-sai.txt b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
>>>> new file mode 100644
>>>> index 0000000..b3be26d
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
>>>> @@ -0,0 +1,79 @@
>>>> +STMicroelectronics STM32 Serial Audio Interface (SAI).
>>>> +
>>>> +The SAI interface (Serial Audio Interface) offers a wide set of audio protocols
>>>> +as I2S standards, LSB or MSB-justified, PCM/DSP, TDM, and AC'97.
>>>> +The SAI contains two independent audio sub-blocks. Each sub-block has
>>>> +its own clock generator and I/O lines controller.
>>>> +
>>>> +Required properties:
>>>> +  - compatible: Should be "st,stm32f4-sai"
>>>> +  - reg: Base address and size of SAI common register set.
>>>> +  - clocks: Must contain phandle and clock specifier pairs for each entry
>>>> +    in clock-names.
>>>> +  - clock-names: Must contain "clk_x8k" and "clk_x11k"
>>>> +    "clk_x8k": SAI parent clock for sampling rates multiple of 8kHz.
>>>> +    "clk_x11k": SAI parent clock for sampling rates multiple of 11.025kHz.
>>>
>>> clk_ is redundant.
>>>
>>
>> Do you mean, removing clk_ prefix ?
>
> Yes.
>
>>
>>>> +  - interrupts: cpu DAI interrupt line shared by SAI sub-blocks
>>>> +
>>>> +Note: Each SAI controller should have an alias correctly numbered
>>>> +in "aliases" node, to provide explicit name to CPU DAI.
>>>
>>> No, it shouldn't. Why do you need that?
>>>
>>
>> Yes, this is not mandatory. This is convenient to identify sai
>> controller, as we may have up to 8 instances.
>> I can make it optional, or remove it if you think it is not relevant.
>
> Remove it.
>

One more thing regarding aliases.
In future patches, I will add alsa controls to configure sai.
Some stm32 socs exhibit several sai (4 instances for H7)
It will be necessary to identify to which sai each control apply,
through the control names:
	SAI1A control X
	SAI2A control X
	...
sub-node compatible already allows to identify A or B sub-instance.

An alternative to alias, may be to use dev_name information to identify 
sai instance. But this does not produce user friendly control names.

Another way is to use compatible also. The drawback here
is to multiply compatible names. (many soc families and many instances)

What is your recommendation ?
If there is another solution, I did not consider, please let me know.

>>
>>>
>>>> +
>>>> +Optional properties:
>>>> +  - resets: Reference to a reset controller asserting the SAI
>>>> +
>>>> +SAI subnodes:
>>>> +Two subnodes corresponding to SAI sub-block instances A et B can be defined.
>>>> +Subnode can be omitted for unsused sub-block.
>>>> +
>>>> +SAI subnodes required properties:
>>>> +  - compatible: Should be "st,stm32-sai-sub-a" or "st,stm32-sai-sub-b"
>>>> +    for SAI sub-block A or B respectively.
>>>> +  - reg: Base address and size of SAI sub-block register set.
>>>> +  - clocks: Must contain one phandle and clock specifier pair
>>>> +    for sai_ck which feeds the internal clock generator.
>>>> +  - clock-names: Must contain "sai_ck".
>>>> +  - dmas: see Documentation/devicetree/bindings/dma/stm32-dma.txt
>>>> +  - dma-names: identifier string for each DMA request line
>>>> +    "tx": if sai sub-block is configured as playback DAI
>>>> +    "rx": if sai sub-block is configured as capture DAI
>>>> +  - pinctrl-names: should contain only value "default"
>>>> +  - pinctrl-0: see Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt
>>>> +
>>>> +Example:
>>>> +sai1: sai1@40015800 {
>>>> +    compatible = "st,stm32f4-sai";
>>>> +    reg = <0x40015800 0x400>;
>>
>>         reg = <0x40015800 0x4>;
>>
>>>> +    clocks = <&rcc 1 CLK_SAIQ_PDIV>, <&rcc 1 CLK_I2SQ_PDIV>;
>>>> +    clock-names = "clk_x8k", "clk_x11k";
>>>> +    interrupts = <87>;
>>>> +    resets = <&rcc 310>;
>>>> +
>>>> +    sai1b: sai@1 {
>>>
>>> unit address needs a reg property.
>>>
>>> audio-controller@1
>>>
>>
>> Right. This needs to be updated as follows:
>>         sai1b: sai1b@40015824 {
>
> audio-controller@...
>
>>                 ...
>>                 reg = <0x40015824 0x1C>;
>>                 ...
>>         };
>>
>>>> +            #sound-dai-cells = <0>;
>>>> +            compatible = "st,stm32-sai-sub-b";
>>>> +            clocks = <&rcc 1 CLK_SAI2>;
>>>> +            clock-names = "sai_ck";
>>>> +            dmas = <&dma2 5 0 0x400 0x1>;
>>>> +            dma-names = "tx";
>>>> +    };
>>>> +};
>>>> +
>>>> +sound {
>>>> +    compatible = "simple-audio-card";
>>>
>>> Perhaps you want to use the graph-card here. It's getting close to
>>> merging.
>>>
>>
>> mclk-fs property is required when SAI is configured as master.
>> It seems that mclk-fs is not supported in current version
>> of audio graph card. So I thing I should keep simple card for the time
>> being. Anyway, I plan further updates for SAI, so I will
>> have opportunity to change to graph card at that time.
>
> Well, it's not easy to switch later and maintain compatibility. Is it
> complicated to add mclk-fs property? The intent is graph-card supports
> everything simple-card supports.
>
> Rob
>

Right, it should not be too complicated to add mclk-fs support to 
graph-card.

BRs
olivier

[RESEND PATCH v2 0/2] Add STM32 SAI support

[olivier moysan]

This patch-set handles the Serial Audio Interface (SAI) IP on STM32 platforms.

The SAI IP is composed of two Sub-block A and B. (see the figure below)
Each sub-block makes use of individual and shared resources.

Shared resources:
	- Reset line. Reset common and sub-block registers.
	- Bus interface clocks. This clock is not exposed in device
	as it it managed by clock driver, according to kernel clocks gating.
	- Common register. SAI IP exhibits a common configuration register
	to manage synchronization modes. NB: These modes are not yet implemented
	in this version of the SAI driver.
	- Interrupt. Sub-blocks have their own interrupt status registers but they 
	share the same interrupt line.

Individual resources:
	- Register set
	- DMA request line.
	- Communication interface. 
	Each sub-block has its own GPIOs and associated bus lines.
	- Kernel clock. 
	Each sub-block has its own dedicated clock for its communication interface.

To reflect this architecture Sub-block A and B are handled by 2 child devices.
Sub-block A and B devices can be configured independently either as transmitter
or receiver. A PCM device is associated to each sub-block.

A sub-block has to select the appropriated parent clock at runtime, 
depending on the audio stream sampling rate to be played or captured.
Two parent clocks must be provided to support sampling rates multiples
of 8 kHz or 11.025kHz.

 Interface clock  +--------------------------------+
+---------------> | SAI IP                         |
 Reset            |     +-----------------+        |
+---------------> |     |common registers |        |
                  |     +-----------------+        |
                  |                                |
                  |    +----------------------+    |
                  |    | Sub-block A          |    |
 Kernel clock A   |    |                      |    | Bus A
+--------------------> | +----------------+   +---------------->
                  |    | |A registers     |   |    |
                  |    | +----------------+   |    |
                  |    +----------------------+    |
                  |                                |
                  |    +----------------------+    |
                  |    | Sub-block B          |    |
 Kernel clock B   |    |                      |    | Bus B
+--------------------> | +----------------+   +----------------->
                  |    | |B registers     |   |    |
                  |    | +----------------+   |    |
                  |    +----------------------+    |
                  |                                |
                  +--------------------------------+

Changes in v2:
	- Fix warnings

olivier moysan (2):
  ASoC: stm32: add bindings for SAI
  ASoC: stm32: add SAI driver

 .../devicetree/bindings/sound/st,stm32-sai.txt     |  79 ++
 sound/soc/Kconfig                                  |   1 +
 sound/soc/Makefile                                 |   1 +
 sound/soc/stm/Kconfig                              |   8 +
 sound/soc/stm/Makefile                             |   6 +
 sound/soc/stm/stm32_sai.c                          | 123 +++
 sound/soc/stm/stm32_sai.h                          | 202 +++++
 sound/soc/stm/stm32_sai_sub.c                      | 899 +++++++++++++++++++++
 8 files changed, 1319 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/sound/st,stm32-sai.txt
 create mode 100644 sound/soc/stm/Kconfig
 create mode 100644 sound/soc/stm/Makefile
 create mode 100644 sound/soc/stm/stm32_sai.c
 create mode 100644 sound/soc/stm/stm32_sai.h
 create mode 100644 sound/soc/stm/stm32_sai_sub.c

-- 
1.9.1

[RESEND PATCH v2 1/2] ASoC: stm32: add bindings for SAI

[olivier moysan]

This patch adds documentation of device tree bindings for the
STM32 SAI ASoC driver.

Signed-off-by: olivier moysan <olivier.moysan@st.com>
---
 .../devicetree/bindings/sound/st,stm32-sai.txt     | 79 ++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/sound/st,stm32-sai.txt

diff --git a/Documentation/devicetree/bindings/sound/st,stm32-sai.txt b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
new file mode 100644
index 0000000..b3be26d
--- /dev/null
+++ b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
@@ -0,0 +1,79 @@
+STMicroelectronics STM32 Serial Audio Interface (SAI).
+
+The SAI interface (Serial Audio Interface) offers a wide set of audio protocols
+as I2S standards, LSB or MSB-justified, PCM/DSP, TDM, and AC'97.
+The SAI contains two independent audio sub-blocks. Each sub-block has
+its own clock generator and I/O lines controller.
+
+Required properties:
+  - compatible: Should be "st,stm32f4-sai"
+  - reg: Base address and size of SAI common register set.
+  - clocks: Must contain phandle and clock specifier pairs for each entry
+	in clock-names.
+  - clock-names: Must contain "clk_x8k" and "clk_x11k"
+	"clk_x8k": SAI parent clock for sampling rates multiple of 8kHz.
+	"clk_x11k": SAI parent clock for sampling rates multiple of 11.025kHz.
+  - interrupts: cpu DAI interrupt line shared by SAI sub-blocks
+
+Note: Each SAI controller should have an alias correctly numbered
+in "aliases" node, to provide explicit name to CPU DAI.
+
+Optional properties:
+  - resets: Reference to a reset controller asserting the SAI
+
+SAI subnodes:
+Two subnodes corresponding to SAI sub-block instances A et B can be defined.
+Subnode can be omitted for unsused sub-block.
+
+SAI subnodes required properties:
+  - compatible: Should be "st,stm32-sai-sub-a" or "st,stm32-sai-sub-b"
+	for SAI sub-block A or B respectively.
+  - reg: Base address and size of SAI sub-block register set.
+  - clocks: Must contain one phandle and clock specifier pair
+	for sai_ck which feeds the internal clock generator.
+  - clock-names: Must contain "sai_ck".
+  - dmas: see Documentation/devicetree/bindings/dma/stm32-dma.txt
+  - dma-names: identifier string for each DMA request line
+	"tx": if sai sub-block is configured as playback DAI
+	"rx": if sai sub-block is configured as capture DAI
+  - pinctrl-names: should contain only value "default"
+  - pinctrl-0: see Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt
+
+Example:
+sai1: sai1@40015800 {
+	compatible = "st,stm32f4-sai";
+	reg = <0x40015800 0x400>;
+	clocks = <&rcc 1 CLK_SAIQ_PDIV>, <&rcc 1 CLK_I2SQ_PDIV>;
+	clock-names = "clk_x8k", "clk_x11k";
+	interrupts = <87>;
+	resets = <&rcc 310>;
+
+	sai1b: sai@1 {
+		#sound-dai-cells = <0>;
+		compatible = "st,stm32-sai-sub-b";
+		clocks = <&rcc 1 CLK_SAI2>;
+		clock-names = "sai_ck";
+		dmas = <&dma2 5 0 0x400 0x1>;
+		dma-names = "tx";
+	};
+};
+
+sound {
+	compatible = "simple-audio-card";
+	simple-audio-card,name = "STM32-Sound-Card";
+	status = "okay";
+
+	simple-audio-card,dai-link@0 {
+		format = "i2s";
+		cpu {
+			sound-dai = <&sai1b>;
+		};
+		codec {
+			sound-dai = <&codec>;
+		};
+	};
+};
+
+aliases {
+	sai1 = &sai1;
+};
-- 
1.9.1

Re: [RESEND PATCH v2 1/2] ASoC: stm32: add bindings for SAI

[Rob Herring]

On Tue, Mar 07, 2017 at 10:44:31AM +0100, olivier moysan wrote:
> This patch adds documentation of device tree bindings for the
> STM32 SAI ASoC driver.
> 
> Signed-off-by: olivier moysan <olivier.moysan-qxv4g6HH51o@public.gmane.org>
> ---
>  .../devicetree/bindings/sound/st,stm32-sai.txt     | 79 ++++++++++++++++++++++
>  1 file changed, 79 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/sound/st,stm32-sai.txt
> 
> diff --git a/Documentation/devicetree/bindings/sound/st,stm32-sai.txt b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
> new file mode 100644
> index 0000000..b3be26d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
> @@ -0,0 +1,79 @@
> +STMicroelectronics STM32 Serial Audio Interface (SAI).
> +
> +The SAI interface (Serial Audio Interface) offers a wide set of audio protocols
> +as I2S standards, LSB or MSB-justified, PCM/DSP, TDM, and AC'97.
> +The SAI contains two independent audio sub-blocks. Each sub-block has
> +its own clock generator and I/O lines controller.
> +
> +Required properties:
> +  - compatible: Should be "st,stm32f4-sai"
> +  - reg: Base address and size of SAI common register set.
> +  - clocks: Must contain phandle and clock specifier pairs for each entry
> +	in clock-names.
> +  - clock-names: Must contain "clk_x8k" and "clk_x11k"
> +	"clk_x8k": SAI parent clock for sampling rates multiple of 8kHz.
> +	"clk_x11k": SAI parent clock for sampling rates multiple of 11.025kHz.

clk_ is redundant.

> +  - interrupts: cpu DAI interrupt line shared by SAI sub-blocks
> +
> +Note: Each SAI controller should have an alias correctly numbered
> +in "aliases" node, to provide explicit name to CPU DAI.

No, it shouldn't. Why do you need that?


> +
> +Optional properties:
> +  - resets: Reference to a reset controller asserting the SAI
> +
> +SAI subnodes:
> +Two subnodes corresponding to SAI sub-block instances A et B can be defined.
> +Subnode can be omitted for unsused sub-block.
> +
> +SAI subnodes required properties:
> +  - compatible: Should be "st,stm32-sai-sub-a" or "st,stm32-sai-sub-b"
> +	for SAI sub-block A or B respectively.
> +  - reg: Base address and size of SAI sub-block register set.
> +  - clocks: Must contain one phandle and clock specifier pair
> +	for sai_ck which feeds the internal clock generator.
> +  - clock-names: Must contain "sai_ck".
> +  - dmas: see Documentation/devicetree/bindings/dma/stm32-dma.txt
> +  - dma-names: identifier string for each DMA request line
> +	"tx": if sai sub-block is configured as playback DAI
> +	"rx": if sai sub-block is configured as capture DAI
> +  - pinctrl-names: should contain only value "default"
> +  - pinctrl-0: see Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt
> +
> +Example:
> +sai1: sai1@40015800 {
> +	compatible = "st,stm32f4-sai";
> +	reg = <0x40015800 0x400>;
> +	clocks = <&rcc 1 CLK_SAIQ_PDIV>, <&rcc 1 CLK_I2SQ_PDIV>;
> +	clock-names = "clk_x8k", "clk_x11k";
> +	interrupts = <87>;
> +	resets = <&rcc 310>;
> +
> +	sai1b: sai@1 {

unit address needs a reg property.

audio-controller@1

> +		#sound-dai-cells = <0>;
> +		compatible = "st,stm32-sai-sub-b";
> +		clocks = <&rcc 1 CLK_SAI2>;
> +		clock-names = "sai_ck";
> +		dmas = <&dma2 5 0 0x400 0x1>;
> +		dma-names = "tx";
> +	};
> +};
> +
> +sound {
> +	compatible = "simple-audio-card";

Perhaps you want to use the graph-card here. It's getting close to 
merging.

> +	simple-audio-card,name = "STM32-Sound-Card";
> +	status = "okay";
> +
> +	simple-audio-card,dai-link@0 {
> +		format = "i2s";
> +		cpu {
> +			sound-dai = <&sai1b>;
> +		};
> +		codec {
> +			sound-dai = <&codec>;
> +		};
> +	};
> +};
> +
> +aliases {
> +	sai1 = &sai1;
> +};
> -- 
> 1.9.1
> 
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Re: [RESEND PATCH v2 1/2] ASoC: stm32: add bindings for SAI

[Olivier MOYSAN]

Hello Rob,

Thanks for your feedback.

On 03/15/2017 06:46 PM, Rob Herring wrote:
> On Tue, Mar 07, 2017 at 10:44:31AM +0100, olivier moysan wrote:
>> This patch adds documentation of device tree bindings for the
>> STM32 SAI ASoC driver.
>>
>> Signed-off-by: olivier moysan <olivier.moysan@st.com>
>> ---
>>  .../devicetree/bindings/sound/st,stm32-sai.txt     | 79 ++++++++++++++++++++++
>>  1 file changed, 79 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/sound/st,stm32-sai.txt
>>
>> diff --git a/Documentation/devicetree/bindings/sound/st,stm32-sai.txt b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
>> new file mode 100644
>> index 0000000..b3be26d
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
>> @@ -0,0 +1,79 @@
>> +STMicroelectronics STM32 Serial Audio Interface (SAI).
>> +
>> +The SAI interface (Serial Audio Interface) offers a wide set of audio protocols
>> +as I2S standards, LSB or MSB-justified, PCM/DSP, TDM, and AC'97.
>> +The SAI contains two independent audio sub-blocks. Each sub-block has
>> +its own clock generator and I/O lines controller.
>> +
>> +Required properties:
>> +  - compatible: Should be "st,stm32f4-sai"
>> +  - reg: Base address and size of SAI common register set.
>> +  - clocks: Must contain phandle and clock specifier pairs for each entry
>> +	in clock-names.
>> +  - clock-names: Must contain "clk_x8k" and "clk_x11k"
>> +	"clk_x8k": SAI parent clock for sampling rates multiple of 8kHz.
>> +	"clk_x11k": SAI parent clock for sampling rates multiple of 11.025kHz.
>
> clk_ is redundant.
>

Do you mean, removing clk_ prefix ?

>> +  - interrupts: cpu DAI interrupt line shared by SAI sub-blocks
>> +
>> +Note: Each SAI controller should have an alias correctly numbered
>> +in "aliases" node, to provide explicit name to CPU DAI.
>
> No, it shouldn't. Why do you need that?
>

Yes, this is not mandatory. This is convenient to identify sai 
controller, as we may have up to 8 instances.
I can make it optional, or remove it if you think it is not relevant.

>
>> +
>> +Optional properties:
>> +  - resets: Reference to a reset controller asserting the SAI
>> +
>> +SAI subnodes:
>> +Two subnodes corresponding to SAI sub-block instances A et B can be defined.
>> +Subnode can be omitted for unsused sub-block.
>> +
>> +SAI subnodes required properties:
>> +  - compatible: Should be "st,stm32-sai-sub-a" or "st,stm32-sai-sub-b"
>> +	for SAI sub-block A or B respectively.
>> +  - reg: Base address and size of SAI sub-block register set.
>> +  - clocks: Must contain one phandle and clock specifier pair
>> +	for sai_ck which feeds the internal clock generator.
>> +  - clock-names: Must contain "sai_ck".
>> +  - dmas: see Documentation/devicetree/bindings/dma/stm32-dma.txt
>> +  - dma-names: identifier string for each DMA request line
>> +	"tx": if sai sub-block is configured as playback DAI
>> +	"rx": if sai sub-block is configured as capture DAI
>> +  - pinctrl-names: should contain only value "default"
>> +  - pinctrl-0: see Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt
>> +
>> +Example:
>> +sai1: sai1@40015800 {
>> +	compatible = "st,stm32f4-sai";
>> +	reg = <0x40015800 0x400>;

	reg = <0x40015800 0x4>;

>> +	clocks = <&rcc 1 CLK_SAIQ_PDIV>, <&rcc 1 CLK_I2SQ_PDIV>;
>> +	clock-names = "clk_x8k", "clk_x11k";
>> +	interrupts = <87>;
>> +	resets = <&rcc 310>;
>> +
>> +	sai1b: sai@1 {
>
> unit address needs a reg property.
>
> audio-controller@1
>

Right. This needs to be updated as follows:
	sai1b: sai1b@40015824 {
		...
		reg = <0x40015824 0x1C>;
		...
	};

>> +		#sound-dai-cells = <0>;
>> +		compatible = "st,stm32-sai-sub-b";
>> +		clocks = <&rcc 1 CLK_SAI2>;
>> +		clock-names = "sai_ck";
>> +		dmas = <&dma2 5 0 0x400 0x1>;
>> +		dma-names = "tx";
>> +	};
>> +};
>> +
>> +sound {
>> +	compatible = "simple-audio-card";
>
> Perhaps you want to use the graph-card here. It's getting close to
> merging.
>

mclk-fs property is required when SAI is configured as master.
It seems that mclk-fs is not supported in current version
of audio graph card. So I thing I should keep simple card for the time 
being. Anyway, I plan further updates for SAI, so I will
have opportunity to change to graph card at that time.

>> +	simple-audio-card,name = "STM32-Sound-Card";
>> +	status = "okay";
>> +
>> +	simple-audio-card,dai-link@0 {
>> +		format = "i2s";

		mclk-fs = <256>;

>> +		cpu {
>> +			sound-dai = <&sai1b>;
>> +		};
>> +		codec {
>> +			sound-dai = <&codec>;
>> +		};
>> +	};
>> +};
>> +
>> +aliases {
>> +	sai1 = &sai1;
>> +};
>> --
>> 1.9.1
>>

regards
olivier

Re: [RESEND PATCH v2 1/2] ASoC: stm32: add bindings for SAI

[Rob Herring]

On Thu, Mar 16, 2017 at 5:50 AM, Olivier MOYSAN <olivier.moysan@st.com> wrote:
> Hello Rob,
>
> Thanks for your feedback.
>
> On 03/15/2017 06:46 PM, Rob Herring wrote:
>> On Tue, Mar 07, 2017 at 10:44:31AM +0100, olivier moysan wrote:
>>> This patch adds documentation of device tree bindings for the
>>> STM32 SAI ASoC driver.
>>>
>>> Signed-off-by: olivier moysan <olivier.moysan@st.com>
>>> ---
>>>  .../devicetree/bindings/sound/st,stm32-sai.txt     | 79 ++++++++++++++++++++++
>>>  1 file changed, 79 insertions(+)
>>>  create mode 100644 Documentation/devicetree/bindings/sound/st,stm32-sai.txt
>>>
>>> diff --git a/Documentation/devicetree/bindings/sound/st,stm32-sai.txt b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
>>> new file mode 100644
>>> index 0000000..b3be26d
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/sound/st,stm32-sai.txt
>>> @@ -0,0 +1,79 @@
>>> +STMicroelectronics STM32 Serial Audio Interface (SAI).
>>> +
>>> +The SAI interface (Serial Audio Interface) offers a wide set of audio protocols
>>> +as I2S standards, LSB or MSB-justified, PCM/DSP, TDM, and AC'97.
>>> +The SAI contains two independent audio sub-blocks. Each sub-block has
>>> +its own clock generator and I/O lines controller.
>>> +
>>> +Required properties:
>>> +  - compatible: Should be "st,stm32f4-sai"
>>> +  - reg: Base address and size of SAI common register set.
>>> +  - clocks: Must contain phandle and clock specifier pairs for each entry
>>> +    in clock-names.
>>> +  - clock-names: Must contain "clk_x8k" and "clk_x11k"
>>> +    "clk_x8k": SAI parent clock for sampling rates multiple of 8kHz.
>>> +    "clk_x11k": SAI parent clock for sampling rates multiple of 11.025kHz.
>>
>> clk_ is redundant.
>>
>
> Do you mean, removing clk_ prefix ?

Yes.

>
>>> +  - interrupts: cpu DAI interrupt line shared by SAI sub-blocks
>>> +
>>> +Note: Each SAI controller should have an alias correctly numbered
>>> +in "aliases" node, to provide explicit name to CPU DAI.
>>
>> No, it shouldn't. Why do you need that?
>>
>
> Yes, this is not mandatory. This is convenient to identify sai
> controller, as we may have up to 8 instances.
> I can make it optional, or remove it if you think it is not relevant.

Remove it.

>
>>
>>> +
>>> +Optional properties:
>>> +  - resets: Reference to a reset controller asserting the SAI
>>> +
>>> +SAI subnodes:
>>> +Two subnodes corresponding to SAI sub-block instances A et B can be defined.
>>> +Subnode can be omitted for unsused sub-block.
>>> +
>>> +SAI subnodes required properties:
>>> +  - compatible: Should be "st,stm32-sai-sub-a" or "st,stm32-sai-sub-b"
>>> +    for SAI sub-block A or B respectively.
>>> +  - reg: Base address and size of SAI sub-block register set.
>>> +  - clocks: Must contain one phandle and clock specifier pair
>>> +    for sai_ck which feeds the internal clock generator.
>>> +  - clock-names: Must contain "sai_ck".
>>> +  - dmas: see Documentation/devicetree/bindings/dma/stm32-dma.txt
>>> +  - dma-names: identifier string for each DMA request line
>>> +    "tx": if sai sub-block is configured as playback DAI
>>> +    "rx": if sai sub-block is configured as capture DAI
>>> +  - pinctrl-names: should contain only value "default"
>>> +  - pinctrl-0: see Documentation/devicetree/bindings/pinctrl/pinctrl-stm32.txt
>>> +
>>> +Example:
>>> +sai1: sai1@40015800 {
>>> +    compatible = "st,stm32f4-sai";
>>> +    reg = <0x40015800 0x400>;
>
>         reg = <0x40015800 0x4>;
>
>>> +    clocks = <&rcc 1 CLK_SAIQ_PDIV>, <&rcc 1 CLK_I2SQ_PDIV>;
>>> +    clock-names = "clk_x8k", "clk_x11k";
>>> +    interrupts = <87>;
>>> +    resets = <&rcc 310>;
>>> +
>>> +    sai1b: sai@1 {
>>
>> unit address needs a reg property.
>>
>> audio-controller@1
>>
>
> Right. This needs to be updated as follows:
>         sai1b: sai1b@40015824 {

audio-controller@...

>                 ...
>                 reg = <0x40015824 0x1C>;
>                 ...
>         };
>
>>> +            #sound-dai-cells = <0>;
>>> +            compatible = "st,stm32-sai-sub-b";
>>> +            clocks = <&rcc 1 CLK_SAI2>;
>>> +            clock-names = "sai_ck";
>>> +            dmas = <&dma2 5 0 0x400 0x1>;
>>> +            dma-names = "tx";
>>> +    };
>>> +};
>>> +
>>> +sound {
>>> +    compatible = "simple-audio-card";
>>
>> Perhaps you want to use the graph-card here. It's getting close to
>> merging.
>>
>
> mclk-fs property is required when SAI is configured as master.
> It seems that mclk-fs is not supported in current version
> of audio graph card. So I thing I should keep simple card for the time
> being. Anyway, I plan further updates for SAI, so I will
> have opportunity to change to graph card at that time.

Well, it's not easy to switch later and maintain compatibility. Is it
complicated to add mclk-fs property? The intent is graph-card supports
everything simple-card supports.

Rob