[PATCH] dt-bindings: exynos: Document #sound-dai-cells property of the HDMI node

[Inki Dae]

Hi Marek,

2018년 03월 08일 16:36에 Marek Szyprowski 이(가) 쓴 글:
> Hi Inki,
> 
> On 2018-03-08 07:50, Inki Dae wrote:
>> 2018년 03월 08일 15:29에 Marek Szyprowski 이(가) 쓴 글:
>>> On 2018-03-08 05:01, Inki Dae wrote:
>>>> 2018년 03월 08일 02:11에 Sylwester Nawrocki 이(가) 쓴 글:
>>>>> The #sound-dai-cells DT property is required to describe link between
>>>>> the HDMI IP block and the SoC's audio subsystem.
>>>>>
>>>>> Signed-off-by: Sylwester Nawrocki <s.nawrocki at samsung.com>
>>>>> ---
>>>>>    Documentation/devicetree/bindings/display/exynos/exynos_hdmi.txt | 3 +++
>>>>>    1 file changed, 3 insertions(+)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/display/exynos/exynos_hdmi.txt b/Documentation/devicetree/bindings/display/exynos/exynos_hdmi.txt
>>>>> index 8715ff06c457..6b2a526ec586 100644
>>>>> --- a/Documentation/devicetree/bindings/display/exynos/exynos_hdmi.txt
>>>>> +++ b/Documentation/devicetree/bindings/display/exynos/exynos_hdmi.txt
>>>>> @@ -50,6 +50,9 @@ Required properties for Exynos 5433:
>>>>>    - clock-names: aliases for above clock specfiers.
>>>>>    - samsung,sysreg: handle to syscon used to control the system registers.
>>>>>    +Optional properties for Exynos 4210, 4212, 5420 and 5433:
>>>>> + - #sound-dai-cells: should be 0.
>>>>> +
>>>> Just trivial question. 'sound-dai-cells' property could affect hdmi driver? I looked into HDMI codec driver but I didn't find relevat code.
>>>> I mean that if this property never affect HDMI driver then this property would be a dead thing even through this can be declared optionally.
>>> This property is used by ASoC framework when it is building connections
>>> between all elements of the virtual 'sound card'. It allows generic
>>> code to find proper driver for the digital audio interface (DAI) object.
>> I also assumed that some place of ASoC framework checks this property. For this I looked into HDMI codec driver(sound/soc/codecs/hdmi-codec.c) and relevant interfaces of ASoC framework.
>> But I couldn't find it. :( Could you let me know which code of ASoC framework checks this? I saw this property only in 'snd_soc_of_get_dai_name' and 'snd_soc_of_get_dai_link_codecs' functions but seems these functions aren't called by the HDMI codec driver.
> 
> It is used by snd_soc_of_get_dai_link_codecs() function, which is called
> from respective board/machine driver. See sound/soc/samsung/odroid.c for
> good example. It allows to automatically create connection to max98090 and
> hdmi codec devices, which are specified in 'sound/codec' node (see
> exynos5422-odroidxu3-audio.dtsi).

Ah, sorry, I missed to check that driver and checked only DRM drivers. :)
By the way, it seems 'sound-dai-cells' property never affect Exynos4210/4212/5420/5433. It seems that even through ALSA TM2 audio driver(tm2_wm5110.c) exists the driver never check the property.
However, this patch adds below description.
"Optional properties for Exynos 4210, 4212, 5420 and 5433"

Is there a possibility for other boards based on Exynos4210/4212/5420/5433 SoC to use this property later?

Thanks,
Inki Dae

> 
> Best regards