Re: [PATCH 08/12] dt-bindings: i2c: renesas,riic: Document the R9A08G045 support

claudiu beznea
2024-06-21T14:30:45Z

On 21.06.2024 17:06, Biju Das wrote:
> Hi Claudiu,
>
>> -----Original Message-----
>> From: claudiu beznea <claudiu.beznea@tuxon.dev>
>> Sent: Friday, June 21, 2024 2:30 PM
>> Subject: Re: [PATCH 08/12] dt-bindings: i2c: renesas,riic: Document the R9A08G045 support
>>
>>
>>
>> On 21.06.2024 16:10, Biju Das wrote:
>>>
>>>
>>>> -----Original Message-----
>>>> From: claudiu beznea <claudiu.beznea@tuxon.dev>
>>>> Sent: Friday, June 21, 2024 2:06 PM
>>> Subject: Re: [PATCH 08/12] dt-bindings: i2c: renesas,riic: Document
>>> the R9A08G045 support
>>>>
>>>>
>>>>
>>>> On 21.06.2024 15:56, Biju Das wrote:
>>>>>
>>>>> Hi claudiu,
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: claudiu beznea <claudiu.beznea@tuxon.dev>
>>>>>> Sent: Friday, June 21, 2024 1:55 PM
>>>>>> Subject: Re: [PATCH 08/12] dt-bindings: i2c: renesas,riic: Document
>>>>>> the R9A08G045 support
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 21.06.2024 15:34, Biju Das wrote:
>>>>>>> Hi Claudiu,
>>>>>>>
>>>>>>>> -----Original Message-----
>>>>>>>> From: Claudiu <claudiu.beznea@tuxon.dev>
>>>>>>>> Sent: Friday, June 21, 2024 12:23 PM
>>>>>>>> Subject: [PATCH 08/12] dt-bindings: i2c: renesas,riic: Document
>>>>>>>> the
>>>>>>>> R9A08G045 support
>>>>>>>>
>>>>>>>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>>>>>>
>>>>>>>> Document the Renesas RZ/G3S (R9A08G045) RIIC IP. This is
>>>>>>>> compatible with the version available on Renesas RZ/V2H
>>>>>>>> (R9A09G075). Most of the IP variants that the RIIC driver is working with supports fast mode
>> plus.
>>>>>>>> However, it happens that on the same SoC to have IP instatiations
>>>>>>>> that support fast mode plus as well as IP instantiation that
>>>>>>>> doesn't support it. For this, introduced the renesas,riic-no-fast- mode-plus property.
>>>>>>>>
>>>>>>>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>>>>>>> ---
>>>>>>>> Documentation/devicetree/bindings/i2c/renesas,riic.yaml | 8
>>>>>>>> ++++++++
>>>>>>>> 1 file changed, 8 insertions(+)
>>>>>>>>
>>>>>>>> diff --git
>>>>>>>> a/Documentation/devicetree/bindings/i2c/renesas,riic.yaml
>>>>>>>> b/Documentation/devicetree/bindings/i2c/renesas,riic.yaml
>>>>>>>> index 91ecf17b7a81..c0964edbca69 100644
>>>>>>>> --- a/Documentation/devicetree/bindings/i2c/renesas,riic.yaml
>>>>>>>> +++ b/Documentation/devicetree/bindings/i2c/renesas,riic.yaml
>>>>>>>> @@ -25,6 +25,10 @@ properties:
>>>>>>>> - renesas,riic-r9a07g054 # RZ/V2L
>>>>>>>> - const: renesas,riic-rz # RZ/A or RZ/G2L
>>>>>>>>
>>>>>>>> + - items:
>>>>>>>> + - const: renesas,riic-r9a08g045 # RZ/G3S
>>>>>>>> + - const: renesas,riic-r9a09g057
>>>>>>>> +
>>>>>>>> - const: renesas,riic-r9a09g057 # RZ/V2H(P)
>>>>>>>>
>>>>>>>> reg:
>>>>>>>> @@ -66,6 +70,10 @@ properties:
>>>>>>>> resets:
>>>>>>>> maxItems: 1
>>>>>>>>
>>>>>>>> + renesas,riic-no-fast-mode-plus:
>>>>>>>> + description: specifies if fast mode plus is not supported
>>>>>>>> + type: Boolean
>>>>>>>
>>>>>>> Can't this info, as part of device data?? Based on frequency and
>>>>>>> device data is enough to derive this info??
>>>>>>
>>>>>> We can't rely completely on device data because on RZ/G3S we have 2
>>>>>> RIIC channels that support fast mode plus and 2 that doesn't support it.
>>>>>
>>>>> Can't array of bits for this channels won't help??
>>>>
>>>> Can you give an example? I'm not sure I understand how you would
>>>> prefer me to use the array of bits.
>>>
>>> struct riic_of_data {
>>> u8 regs[RIIC_REG_END];
>>> u16 fast_mode_info info; /* 1 means fast mode plus supported,
>>> starting with channel 0*/ };
>>>
>>> .info = 0x3, means channel 0 and 1 has fast mode plus supported .info
>>> = 0x0, none of the channel supported fast mode plus.
>>
>> If I understand the proposal correctly, a match b/w struct riic_of_data::info bit + frequency and
>> the nodes in device tree is still needed, right? As the RZ/G3S RIIC channels are using the same
>> compatible.
>> W/o a match how I cannot detect in the driver who is, e.g., channel 1 that supports FMP w/o
>> hardcoding some RIIC channel data in the driver (e.g. RIIC channel address)?
>
> bit array gives the capability info on various channels.
>
> If someone define fast_mode_plus frequency in DT node and channel is not fast_mode_plus(from the capability info)
> then you should return error.
>
> Here you need to use SoC specific compatible as each SoC has different capabilities.

And I would add, as it is in this case: there are multiple instantiation of
the RIIC in RZ/G3S SoC. RIIC 0 and 1 supports FMP, RIIC 2 and 3 does not.

For all RIICs (0, 1, 2, 3) we use the same compatible (as all are part of
the same SoC). How to do the match b/w DT RIIC channel and driver with the
solution you propose w/o hardcoding some RIIC channel data in the driver?

>
> Cheers,
> Biju
>
>
>>
>> Also, for future SoCs that will suffer the same symptom but for different channels (and channels
>> with different addresses) the driver will have to be adapted to match b/w the channel bit in struct
>> riic_of_data::info and channel node from DT.
>>
>>>
>>> Cheers,
>>> Biju