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Re: [PATCH 1/6] bus: Add shared MDIO bus framework

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On Tuesday 26 April 2016 10:23:02 Florian Fainelli wrote:
> On 26/04/16 05:13, Andrew Lunn wrote:
> >> 4. Apart from these, by using MDIO mux framework we are making our
> >> non-ethernet PHYs dependent on Linux network drivers which is not
> >> acceptable. What if some product line does not need network subsystem at
> >> all?
> > 
> > This is your only valid point. However, does Broadcom have a product
> > line which does not include networking? Is not Broadcom a network SoC
> > vendor?
> 
> But even with that, there is no reason why we could not decouple the
> PHYLIB MDIO framework from PHYLIB and make it available as a more
> standalone subsystem which can be utilized when you have a mix of MDIO
> devices like here.

[adding Kishon Vijay Abraham]

We should also consider how this fits in with drivers/phy/, which is
the generic framework for all PHY devices that are not for ethernet.

The most straightforward way that you mention would be to allow
generic PHY devices to be probed on an MIO bus or mux. This should
just work using mdio_module_driver(), as Andrew already explained.

A more complex problem would be having a PHY driver for a device
that can be either an ethernet phy or some other phy. With today's
frameworks that would require two separate drivers, one in drivers/phy
and one in drivers/net/phy/. If that turns out to be a common problem,
we might want to come up with a way to nest one on top of the other,
or merge two two device structures (struct phy_device and struct phy).

> I am not clear on how common a shared MDIO bus is on other SoCs, but the
> other Broadcom SoCs I am familiar with have dedicated MDIO buses
> instances per type of PHY (PCIe, BUSB, Ethernet), thus making the split
> a ton easier.

I think most commonly, the other PHYs are not on MDIO at all, but are
integrated inside of the SoC as an MMIO based device.

	Arnd

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[PATCH 0/6] Add Shared MDIO framework for iProc based SoCs Pramod Kumar <pramod.kumar@broadcom.com> - 2016-04-21 11:20 +0200
  [PATCH 1/6] bus: Add shared MDIO bus framework Pramod Kumar <pramod.kumar@broadcom.com> - 2016-04-21 11:30 +0200
    Re: [PATCH 1/6] bus: Add shared MDIO bus framework David Miller <davem@davemloft.net> - 2016-04-24 20:20 +0200
      RE: [PATCH 1/6] bus: Add shared MDIO bus framework Pramod Kumar <pramod.kumar@broadcom.com> - 2016-04-25 06:20 +0200
    Re: [PATCH 1/6] bus: Add shared MDIO bus framework Andrew Lunn <andrew@lunn.ch> - 2016-04-25 23:00 +0200
      RE: [PATCH 1/6] bus: Add shared MDIO bus framework Pramod Kumar <pramod.kumar@broadcom.com> - 2016-04-26 10:40 +0200
        Re: [PATCH 1/6] bus: Add shared MDIO bus framework Andrew Lunn <andrew@lunn.ch> - 2016-04-26 14:20 +0200
          Re: [PATCH 1/6] bus: Add shared MDIO bus framework David Miller <davem@davemloft.net> - 2016-04-26 18:30 +0200
          Re: [PATCH 1/6] bus: Add shared MDIO bus framework Florian Fainelli <f.fainelli@gmail.com> - 2016-04-26 19:30 +0200
            Re: [PATCH 1/6] bus: Add shared MDIO bus framework Andrew Lunn <andrew@lunn.ch> - 2016-04-26 19:50 +0200
            Re: [PATCH 1/6] bus: Add shared MDIO bus framework Arnd Bergmann <arnd@arndb.de> - 2016-04-26 20:00 +0200
              Re: [PATCH 1/6] bus: Add shared MDIO bus framework Andrew Lunn <andrew@lunn.ch> - 2016-04-26 20:30 +0200
                Re: [PATCH 1/6] bus: Add shared MDIO bus framework Arnd Bergmann <arnd@arndb.de> - 2016-04-26 21:30 +0200
                Re: [PATCH 1/6] bus: Add shared MDIO bus framework Andrew Lunn <andrew@lunn.ch> - 2016-04-26 21:50 +0200
                Re: [PATCH 1/6] bus: Add shared MDIO bus framework Anup Patel <anup.patel@broadcom.com> - 2016-04-27 06:50 +0200
                Re: [PATCH 1/6] bus: Add shared MDIO bus framework Arnd Bergmann <arnd@arndb.de> - 2016-04-27 11:30 +0200
  [PATCH 6/6] net:phy: Add Ethernet Master for iProc Shared MDIO Controller Pramod Kumar <pramod.kumar@broadcom.com> - 2016-04-21 11:30 +0200
  [PATCH 5/6] Documentation: Binding doc for ethernet master in NS2 Pramod Kumar <pramod.kumar@broadcom.com> - 2016-04-21 11:30 +0200
    Re: [PATCH 5/6] Documentation: Binding doc for ethernet master in NS2 Rob Herring <robh@kernel.org> - 2016-04-22 22:20 +0200
      RE: [PATCH 5/6] Documentation: Binding doc for ethernet master in NS2 Pramod Kumar <pramod.kumar@broadcom.com> - 2016-04-25 06:50 +0200
  Re: [PATCH 0/6] Add Shared MDIO framework for iProc based SoCs Andrew Lunn <andrew@lunn.ch> - 2016-04-25 17:30 +0200

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