Messages in this thread |  | | Subject | Re: [PATCH v3 04/10] Documentations: dt-bindings: Add a document of PECI adapter driver for Aspeed AST24xx/25xx SoCs | From | Jae Hyun Yoo <> | Date | Wed, 18 Apr 2018 09:45:56 -0700 |
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On 4/18/2018 6:59 AM, Rob Herring wrote: > On Tue, Apr 17, 2018 at 5:06 PM, Jae Hyun Yoo > <jae.hyun.yoo@linux.intel.com> wrote: >> On 4/17/2018 11:16 AM, Jae Hyun Yoo wrote: >>> >>> On 4/17/2018 6:16 AM, Rob Herring wrote: >>>> >>>> On Mon, Apr 16, 2018 at 6:12 PM, Jae Hyun Yoo >>>> <jae.hyun.yoo@linux.intel.com> wrote: >>>>> >>>>> On 4/16/2018 11:10 AM, Rob Herring wrote: >>>>>> >>>>>> >>>>>> On Tue, Apr 10, 2018 at 11:32:06AM -0700, Jae Hyun Yoo wrote: >>>>>>> >>>>>>> >>>>>>> This commit adds a dt-bindings document of PECI adapter driver for >>>>>>> Aspeed >>>>>>> AST24xx/25xx SoCs. >>>> >>>> >>>> [...] >>>> >>>>>>> +- clocks : Should contain clock source for PECI >>>>>>> controller. >>>>>>> + Should reference clkin. >>>>>>> +- clock_frequency : Should contain the operation frequency of PECI >>>>>>> controller >>>>>>> + in units of Hz. >>>>>>> + 187500 ~ 24000000 >>>>>> >>>>>> >>>>>> >>>>>> This is the frequency of the bus or used to derive it? It would be >>>>>> better to specify the bus frequency instead and have the driver >>>>>> calculate its internal freq. And then use "bus-frequency" instead. >>>>>> >>>>> >>>>> I agree with you. Actually, it is being used for operation frequency >>>>> setting >>>>> of PECI controller module in SoC so it's different from the meaning of >>>>> "bus-frequency". I'll change it to "operation-frequency". >>>> >>>> >>>> No, now you've gone from a standard property name to something custom. >>>> Why do you need to set the frequency in DT if it is not related to the >>>> interface frequency? >>>> >>>> Rob >>>> >>> >>> Actually, the interface frequency is affected by the operation frequency >>> but there is no description of its relationship in datasheet. I'll check >>> again about the detail to ASPEED chip vendor and will use >>> 'bus-frequency' if available. >>> >> >> I investigated it more deeply. Basically, by the spec, PECI bus speed >> cannot be set as a fixed speed. A PECI bus can have a wide speed range >> from 2Kbps to 2Mbps which is dynamically set by a handshaking sequence >> between an originator and clients called 'timing negotiation' in spec. >> This timing negotiation behavior happens on every single transaction so the >> bus speed also can vary on every transactions. So I'm thinking a custom >> property name for it, 'peci-clk-frequency' if it is acceptable. > > Okay, seems bus-frequency is not appropriate here. So use > 'clock-frequency' (note the '-' not '_' as that is the standard > property). > > Rob >
Thanks! I'll use 'clock-frequency' for it.
Jae
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