[alsa-devel] [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 at 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 at 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 at 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 at 1 {
>>
>> unit address needs a reg property.
>>
>> audio-controller at 1
>>
>
> Right. This needs to be updated as follows:
>         sai1b: sai1b at 40015824 {

audio-controller at ...

>                 ...
>                 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