netdev - Re: [PATCH net-next 0/3] net: phy: Support enabling clocks prior to bus probe

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Message-ID: <ed801431-2b46-5d6d-0cfd-a4b043702f9f@arf.net.pl>
Date:   Fri, 4 Sep 2020 16:00:55 +0200
From:   Adam Rudziński <adam.rudzinski@....net.pl>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org,
        m.felsch@...gutronix.de, hkallweit1@...il.com,
        richard.leitner@...data.com, zhengdejin5@...il.com,
        devicetree@...r.kernel.org, kernel@...gutronix.de, kuba@...nel.org,
        robh+dt@...nel.org
Subject: Re: [PATCH net-next 0/3] net: phy: Support enabling clocks prior to
 bus probe

W dniu 2020-09-04 o 15:45, Andrew Lunn pisze:
>> Just a bunch of questions.
>>
>> Actually, why is it necessary to have a full MDIO bus scan already during
>> probing peripherals?
> That is the Linux bus model. It does not matter what sort of bus it
> is, PCI, USB, MDIO, etc. When the bus driver is loaded, the bus is
> enumerated and drivers probe for each device found on the bus.

OK. But is it always expected to find all the devices on the bus in the 
first run? Does the bus model ever allow to just add any more devices? 
Kind of, "hotplug". :)

>> I'd say that it is not necessary to have a PHY getting found before it is
>> needed to setup the complete interface.
> It is like saying, we don't need to probe the keyboard until the first
> time the "Press Enter" prompt is given?

I'm not sure what you mean. It's like saying that we don't need to care 
if we even have the keyboard until we are interested in any interaction 
with it. (This might be reading a key, an autotest, ..., or not using, 
but avoiding a conflict - depends on application.)

Best regards,
Adam