Re: [net-next,PATCH 4/4] dt-bindings: mdio-ipq4019: add clock support

From: Florian Fainelli
Date: Thu Jul 02 2020 - 16:04:45 EST




On 7/2/2020 12:18 PM, Robert Marko wrote:
> On Thu, Jul 2, 2020 at 3:38 PM Andrew Lunn <andrew@xxxxxxx> wrote:
>>
>>> + clock-frequency:
>>> + default: 100000000
>>
>> IEEE 802.3 says the default should be 2.5MHz. Some PHYs will go
>> faster, but 100MHz seems unlikely!
> This MDIO controller has an internal divider, by default its set for
> 100MHz clock.
> In IPQ4019 MDIO clock is not controllable but in IPQ6018 etc it's controllable.
> That is the only combination I have currently seen used by Qualcomm.

Not sure I understand here, the 'clock-frequency' is supposed to denote
the MDIO bus output clock frequency, that is the frequency at which all
MDIO devices are going to operate at. Is this 100MHz a clock that feeds
into the MDIO block and get internally divided by a programmable
register to obtain an output MDIO clock?
--
Florian