linux-kernel - Re: [PATCH v4 02/13] dt-bindings: Add bindings for peci-aspeed

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Message-ID: <1398354F-F251-4CEA-8E92-7C442287F6BC@aspeedtech.com>
Date:   Wed, 8 Dec 2021 02:23:16 +0000
From:   Billy Tsai <billy_tsai@...eedtech.com>
To:     "Winiarska, Iwona" <iwona.winiarska@...el.com>,
        "zweiss@...inix.com" <zweiss@...inix.com>
CC:     "corbet@....net" <corbet@....net>,
        "jae.hyun.yoo@...ux.intel.com" <jae.hyun.yoo@...ux.intel.com>,
        "robh@...nel.org" <robh@...nel.org>,
        "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
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Subject: Re: [PATCH v4 02/13] dt-bindings: Add bindings for peci-aspeed


Hi Iwona,

On 2021/12/8, 2:30 AM, "Winiarska, Iwona" <iwona.winiarska@...el.com> wrote:

    On Thu, 2021-12-02 at 02:31 +0000, Billy Tsai wrote:
    >   > Hi Zev,
    >   > 
    >   > On 2021/12/2, 9:55 AM, "Zev Weiss" <zweiss@...inix.com> wrote:
    >   > 
    >   >     On Wed, Dec 01, 2021 at 02:38:04AM PST, Billy Tsai wrote:
    >   >     >   >Hi,
    >   >     >   >
    >   >     >   >On 2021/11/23, 10:10 PM, "openbmc on behalf of Iwona Winiarska"
    >   > <openbmc-bounces+billy_tsai=aspeedtech.com@...ts.ozlabs.org on behalf of
    >   > iwona.winiarska@...el.com> wrote:
    >   >     >   >
    >   >     >   >    Add device tree bindings for the peci-aspeed controller driver.
    >   >     >   >
    >   >     >   >    >   +  aspeed,clock-divider:
    >   >     >   >    >   +    description:
    >   >     >   >    >   +      This value determines PECI controller internal clock
    >   > dividing
    >   >     >   >    >   +      rate. The divider will be calculated as 2 raised to
    >   > the power of
    >   >     >   >    >   +      the given value.
    >   >     >   >    >   +    $ref: /schemas/types.yaml#/definitions/uint32
    >   >     >   >    >   +    minimum: 0
    >   >     >   >    >   +    maximum: 7
    >   >     >   >    >   +    default: 0
    >   >     >   >    >   +
    >   >     >   >    >   +  aspeed,msg-timing:
    >   >     >   >    >   +    description:
    >   >     >   >    >   +      Message timing negotiation period. This value will
    >   > determine the period
    >   >     >   >    >   +      of message timing negotiation to be issued by PECI
    >   > controller. The unit
    >   >     >   >    >   +      of the programmed value is four times of PECI clock
    >   > period.
    >   >     >   >    >   +    $ref: /schemas/types.yaml#/definitions/uint32
    >   >     >   >    >   +    minimum: 0
    >   >     >   >    >   +    maximum: 255
    >   >     >   >    >   +    default: 1
    >   >     >   >    >   +
    >   >     >   >    >   +  aspeed,addr-timing:
    >   >     >   >    >   +    description:
    >   >     >   >    >   +      Address timing negotiation period. This value will
    >   > determine the period
    >   >     >   >    >   +      of address timing negotiation to be issued by PECI
    >   > controller. The unit
    >   >     >   >    >   +      of the programmed value is four times of PECI clock
    >   > period.
    >   >     >   >    >   +    $ref: /schemas/types.yaml#/definitions/uint32
    >   >     >   >    >   +    minimum: 0
    >   >     >   >    >   +    maximum: 255
    >   >     >   >    >   +    default: 1
    >   >     >   >I suggest deleting these three properties and replacing them with the
    >   > following
    >   >     >   >
    >   >     >   >aspeed,peci-bit-time:
    >   >     >   >        description:
    >   >     >   >          The bit time driven by PECI controller. The unit of the
    >   > value is Hz.
    >   >     >   >    minimum: 2000
    >   >     >   >    maximum: 1000000
    >   >     >   >
    >   >     >   >And the driver should use this property to caculate the appropriate
    >   > clock-divider,
    >   >     >   >msg-timing and addr-timing, instead of exposing hardware registers to
    >   > dts.
    >   >     >   >
    >   > 
    >   >     >   Or perhaps just 'bus-frequency' a la i2c-aspeed, gpio-aspeed-sgpio,
    >   > etc?
    >   > 
    >   > It's a good ideal for the consistency.

    >   If we want to go with passing frequency - I would prefer to go with "clock-
    >   frequency" and use clock framework for exposing it to peci-aspeed (as I
    >   mentioned in reply to patch 05).

    >   What do you think?

Good.
It looks that "clock-frequency" is more common usage.

Thanks

Best Regards,
Billy Tsai