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

Biju Das
2024-06-21T14:06:55Z

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.

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