On 28/03/2022 15:19, Sameer Pujar wrote: > > On 28-03-2022 13:37, Krzysztof Kozlowski wrote: >> On 28/03/2022 09:58, Sameer Pujar wrote: >>> On 28-03-2022 12:36, Krzysztof Kozlowski wrote: >>>> External email: Use caution opening links or attachments >>>> >>>> >>>> On 28/03/2022 08:14, Sameer Pujar wrote: >>>>> The rt5658 or rt5659 CODEC system clock (SYSCLK) can be derived from >>>>> various clock sources. For example it can be derived either from master >>>>> clock (MCLK) or by internal PLL. The internal PLL again can take input >>>>> clock references from bit clocks (BCLKs) and MCLK. To enable a flexible >>>>> clocking configuration the DT binding is extended here. >>>>> >>>>> It makes use of standard clock bindings and sets up the clock relation >>>>> via DT. >>>>> >>>>> Signed-off-by: Sameer Pujar <spujar@xxxxxxxxxx> >>>>> Cc: Oder Chiou <oder_chiou@xxxxxxxxxxx> >>>>> --- >>>>> .../devicetree/bindings/sound/realtek,rt5659.yaml | 53 ++++++++++++++++++++-- >>>>> 1 file changed, 49 insertions(+), 4 deletions(-) >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/sound/realtek,rt5659.yaml b/Documentation/devicetree/bindings/sound/realtek,rt5659.yaml >>>>> index b0485b8..0c2f3cb 100644 >>>>> --- a/Documentation/devicetree/bindings/sound/realtek,rt5659.yaml >>>>> +++ b/Documentation/devicetree/bindings/sound/realtek,rt5659.yaml >>>>> @@ -29,12 +29,28 @@ properties: >>>>> maxItems: 1 >>>>> >>>>> clocks: >>>>> - items: >>>>> - - description: Master clock (MCLK) to the CODEC >>>>> + description: | >>>>> + CODEC can receive multiple clock inputs like Master >>>>> + clock (MCLK), I2S bit clocks (BCLK1, BCLK2, BCLK3, >>>>> + BCLK4). The CODEC SYSCLK can be generated from MCLK >>>>> + or internal PLL. In turn PLL can reference from MCLK >>>>> + and BCLKs. >>>>> >>>>> clock-names: >>>>> - items: >>>>> - - const: mclk >>>>> + description: | >>>>> + The clock names can be combination of following: >>>>> + "mclk" : Master clock >>>>> + "pll_ref" : Reference to CODEC PLL clock >>>>> + "sysclk" : CODEC SYSCLK >>>>> + "^bclk[1-4]$" : Bit clocks to CODEC >>>> No, that does not look correct. You allow anything as clock input (even >>>> 20 clocks, different names, any order). That's not how DT schema should >>>> work and that's not how hardware looks like. >>>> Usually the clock inputs are always there which also you mentioned in >>>> description - "multiple clock inputs". All these clocks should be >>>> expected, unless really the wires (physical wires) can be left disconnected. >>> The CODEC can receive multiple clocks but all the input clocks need not >>> be present or connected always. If a specific configuration is needed >>> and platform supports such an input, then all these inputs can be added. >>> I don't know how to define this detail in the schema. If I make all of >>> them expected, then binding check throws errors. If I were to list all >>> the possible combinations, the list is going to be big (not sure if this >>> would be OK?). >> Thanks for explanation. Please differentiate between these two: >> 1. clock inputs connected, but unused (not needed for driver or for >> particular use case), >> 2. clock inputs really not connected. >> >> For the 1. above, such clock inputs should still be listed in the >> bindings and DTS. For the 2. above, such clocks should actually not be >> there. > > Thank you for the suggestion. > >> How to achieve this depends on number of your combinations. IOW, >> how many clocks are physically optional. > > From CODEC point of view all these clock inputs are possible and a > platform may choose to connect a subset of it depending on the > application. The binding is expected to support all such cases. To > support all possibilities, the total combinations can be very big (100+). > >> For some small number of >> variations this can be: >> oneOf: >> - const: mclk >> - items: >> - const: mclk >> - enum: >> - bclk1 >> - bclk2 >> - bclk3 >> - bclk4 >> - items: >> - const: mclk >> - const: pll_ref >> - enum: >> - bclk1 >> - bclk2 >> - bclk3 >> - bclk4 >> >> For a total flexibility that any clock input can be disconnected, this >> should be a list of enums I guess (with minItems). However please find >> the clocks always connected and include them if possible in a fixed way >> (like this oneOf above). > > May be I can list the most commonly required combinations like below and > extend it whenever there is a need for specific combination? Yes, this would work. Relaxing such constraints is possible. Best regards, Krzysztof
