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Date:	Mon, 30 Jun 2014 14:27:42 -0700
From:	Florian Fainelli <>
To:	Vince Bridgers <>
Cc:	Randy Dunlap <>,
	David Miller <>,
	netdev <>,
Subject: Re: [PATCH net v4 1/3] net: libphy: Add phy specific function to
 access mmd phy registers

Hi Vince,

2014-06-29 18:35 GMT-07:00 Vince Bridgers <>:
> libphy was originally written assuming all phy devices support clause 45
> access extensions to the mmd registers through the indirection registers
> located within the first 16 phy registers. This assumption is not true
> in all cases, and one specific example is the Micrel ksz9021 10/100/1000
> Mbps phy. Using the stmmac driver, accessing the mmd registers to query
> and configure energy efficient Ethernet (EEE) features yielded unexpected
> behavior.
> This patch adds mmd access functions to the phy driver that can be
> overriden by the phy specific driver if the phy does not support this
> mechanism or uses it's own non-standard access mechanism. By default,
> the IEEE Compatible clause 45 access mechanism described in clause 22
> is used. With this patch, EEE query/configure functions as expected
> using the stmmac and the Micrel ksz9021 phy.
> Signed-off-by: Vince Bridgers <>

Just one minor nit before this series can go in


> - * phy_read_mmd_indirect - reads data from the MMD registers
> - * @bus: the target MII bus
> + * gen_rd_mmd_indirect - reads data from the MMD registers
> + * @phydev: The PHY device bus
>   * @prtad: MMD Address
>   * @devad: MMD DEVAD
>   * @addr: PHY address on the MII bus
> @@ -935,18 +935,18 @@ static inline void mmd_phy_indirect(struct mii_bus *bus, int prtad, int devad,
>   * 3) Write reg 13 // MMD Data Command for MMD DEVAD
>   * 3) Read  reg 14 // Read MMD data
>   */
> -static int phy_read_mmd_indirect(struct mii_bus *bus, int prtad, int devad,
> -                                int addr)
> +int gen_rd_mmd_indirect(struct phy_device *phydev, int prtad, int devad,
> +                       int addr)
>  {
> -       mmd_phy_indirect(bus, prtad, devad, addr);
> +       mmd_phy_indirect(phydev->bus, prtad, devad, addr);
>         /* Read the content of the MMD's selected register */
> -       return bus->read(bus, addr, MII_MMD_DATA);
> +       return phydev->bus->read(phydev->bus, addr, MII_MMD_DATA);

Throughout the PHY library, phy_* prefix means that this function will
perform the required level of abstraction, that is either using the
driver defined function, or falling back to the generic one.

I would like to reduce the number of changes involved here and keep
phy_read_mmd_indirect, but have it check the driver specific
implementation and fallback to the generic one.
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