netdev - RE: [PATCH v5] net/phy: micrel: Add OF configuration support for ksz9021

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Date:	Tue, 20 Aug 2013 08:50:00 +0000
From:	Duan Fugang-B38611 <B38611@...escale.com>
To:	Sean Cross <xobs@...agi.com>, Sascha Hauer <s.hauer@...gutronix.de>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	"stephen@...workplumber.org" <stephen@...workplumber.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: RE: [PATCH v5] net/phy: micrel: Add OF configuration support for
 ksz9021

From: Sean Cross [mailto:xobs@...agi.com]
Data: Tuesday, August 20, 2013 4:35 PM

> To: Sascha Hauer
> Cc: Duan Fugang-B38611; netdev@...r.kernel.org; devicetree@...r.kernel.org;
> David Miller; stephen@...workplumber.org; Steven Rostedt
> Subject: Re: [PATCH v5] net/phy: micrel: Add OF configuration support for
> ksz9021
> 
> 
> 
> 
> On Monday, August 5, 2013 at 4:12 PM, Sean Cross wrote:
> 
> >
> > On Monday, August 5, 2013 at 3:58 PM, Sascha Hauer wrote:
> >
> > > On Mon, Aug 05, 2013 at 07:04:08AM +0000, Sean Cross wrote:
> > > > Some boards require custom PHY configuration, for example due to
> > > > trace length differences. Add the ability to configure these
> > > > registers in order to get the PHY to function on boards that need it.
> > > >
> > > > Because PHYs are auto-detected based on MDIO device IDs, allow PHY
> > > > configuration to be specified in the parent Ethernet device node
> > > > if no PHY device node is present.
> > > >
> > > > Signed-off-by: Sean Cross <xobs@...agi.com
> > > > (mailto:xobs@...agi.com)

Reviewed-by: Fugang Duan  <B38611@...escale.com>

Do somebody have other suggestion for the patch ?

> > > > ---
> > > > .../devicetree/bindings/net/micrel-ksz9021.txt | 49 ++++++++++
> > > > drivers/net/phy/micrel.c | 101 +++++++++++++++++++-
> > > > 2 files changed, 149 insertions(+), 1 deletion(-) create mode
> > > > 100644 Documentation/devicetree/bindings/net/micrel-ksz9021.txt
> > > >
> > > > diff --git
> > > > a/Documentation/devicetree/bindings/net/micrel-ksz9021.txt
> > > > b/Documentation/devicetree/bindings/net/micrel-ksz9021.txt
> > > > new file mode 100644
> > > > index 0000000..338a7e2
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/net/micrel-ksz9021.txt
> > > > @@ -0,0 +1,49 @@
> > > > +Micrel KSZ9021 Gigabit Ethernet PHY
> > > > +
> > > > +Some boards require special tuning values, particularly when it
> > > > +comes to clock delays. You can specify clock delay values by
> > > > +adding micrel-specific properties to an Ethernet OF device node.
> > > > +
> > > > +All skew control options are specified in picoseconds. The
> > > > +minimum value is 0, and the maximum value is 3000.
> > > > +
> > > > +Optional properties:
> > > > + - rxc-skew : Skew control of RXC pad
> > > > + - rxdv-skew : Skew control of RX CTL pad
> > > > + - txc-skew : Skew control of TXC pad
> > > > + - txen-skew : Skew control of TX_CTL pad
> > > > + - rxd0-skew : Skew control of RX data 0 pad
> > > > + - rxd1-skew : Skew control of RX data 1 pad
> > > > + - rxd2-skew : Skew control of RX data 2 pad
> > > > + - rxd3-skew : Skew control of RX data 3 pad
> > > > + - txd0-skew : Skew control of TX data 0 pad
> > > > + - txd1-skew : Skew control of TX data 1 pad
> > > > + - txd2-skew : Skew control of TX data 2 pad
> > > > + - txd3-skew : Skew control of TX data 3 pad
> > > > +
> > > > +Examples:
> > > > +
> > > > + /* Attach to an Ethernet device with autodetected PHY */ &enet {
> > > > + rxc-skew = <3000>; // picoseconds rxdv-skew = <0>; //
> > > > + picoseconds txc-skew = <3000>; // picoseconds txen-skew = <0>;
> > > > + // picoseconds status = "okay"; };
> > > > +
> > > > + /* Attach to an explicitly-specified PHY */ mdio {
> > > > + phy0: ethernet-phy@0 {
> > > > + rxc-skew = <3000>; // picoseconds rxdv-skew = <0>; //
> > > > + picoseconds txc-skew = <3000>; // picoseconds txen-skew = <0>;
> > > > + // picoseconds reg = <0>; }; };
> > > > + ethernet@...00 {
> > > > + status = "okay";
> > > > + phy = <&phy0>;
> > > > + phy-mode = "rgmii-id";
> > > > + };
> > > > diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
> > > > index 2510435..3e60ed0 100644
> > > > --- a/drivers/net/phy/micrel.c
> > > > +++ b/drivers/net/phy/micrel.c
> > > > @@ -25,6 +25,7 @@
> > > > #include <linux/module.h>
> > > > #include <linux/phy.h>
> > > > #include <linux/micrel_phy.h>
> > > > +#include <linux/of.h>
> > > >
> > > > /* Operation Mode Strap Override */ #define MII_KSZPHY_OMSO 0x16
> > > > @@ -53,6 +54,18 @@ #define KS8737_CTRL_INT_ACTIVE_HIGH (1 << 14)
> > > > #define KSZ8051_RMII_50MHZ_CLK (1 << 7)
> > > >
> > > > +/* Write/read to/from extended registers */ #define
> > > > +MII_KSZPHY_EXTREG 0x0b #define KSZPHY_EXTREG_WRITE 0x8000
> > > > +
> > > > +#define MII_KSZPHY_EXTREG_WRITE 0x0c #define
> > > > +MII_KSZPHY_EXTREG_READ 0x0d
> > > > +
> > > > +/* Extended registers */
> > > > +#define MII_KSZPHY_CLK_CONTROL_PAD_SKEW 0x104 #define
> > > > +MII_KSZPHY_RX_DATA_PAD_SKEW 0x105 #define
> > > > +MII_KSZPHY_TX_DATA_PAD_SKEW 0x106
> > > > +
> > > > static int ksz_config_flags(struct phy_device *phydev) { int
> > > > regval; @@ -65,6 +78,20 @@ static int ksz_config_flags(struct
> > > > phy_device *phydev) return 0; }
> > > >
> > > > +static int kszphy_extended_write(struct phy_device *phydev,
> > > > + u32 regnum, u16 val)
> > > > +{
> > > > + phy_write(phydev, MII_KSZPHY_EXTREG, KSZPHY_EXTREG_WRITE |
> > > > +regnum);  return phy_write(phydev, MII_KSZPHY_EXTREG_WRITE, val);
> > > > +}
> > > > +
> > > > +static int kszphy_extended_read(struct phy_device *phydev,
> > > > + u32 regnum)
> > > > +{
> > > > + phy_write(phydev, MII_KSZPHY_EXTREG, regnum);  return
> > > > +phy_read(phydev, MII_KSZPHY_EXTREG_READ); }
> > > > +
> > > > static int kszphy_ack_interrupt(struct phy_device *phydev) {
> > > > /* bit[7..0] int status, which is a read and clear register. */ @@
> > > > -141,6 +168,78 @@ static int ks8051_config_init(struct phy_device
> > > > *phydev) return rc < 0 ? rc : 0; }
> > > >
> > > > +static int ksz9021_load_values_from_of(struct phy_device *phydev,
> > > > +struct device_node *of_node, u16 reg,  char *field1, char
> > > > +*field2,  char *field3, char *field4) {  int val1 = -1;  int val2
> > > > += -2;  int val3 = -3;  int val4 = -4;  int newval;  int matches =
> > > > +0;
> > > > +
> > > > + if (!of_property_read_u32(of_node, field1, &val1))
> > > > + matches++;
> > > > +
> > > > + if (!of_property_read_u32(of_node, field2, &val2))
> > > > + matches++;
> > > > +
> > > > + if (!of_property_read_u32(of_node, field3, &val3))
> > > > + matches++;
> > > > +
> > > > + if (!of_property_read_u32(of_node, field4, &val4))
> > > > + matches++;
> > > > +
> > > > + if (!matches)
> > > > + return 0;
> > > > +
> > > > + if (matches < 4)
> > > > + newval = kszphy_extended_read(phydev, reg); else newval = 0;
> > >
> > >
> > >
> > >
> > >
> > > Just initialize newval with the reset default of this register. It
> > > will make this function easier. Also this two step read from dt and
> > > evaluate afterwards seems unnecessary.
> >
> >
> >
> > The documentation seems inaccurate here. My datasheet says it defaults
> to 0x0111, but when I check it for myself it comes out 0x7777. Which value
> do you think I should take?
> > > > +
> > > > + if (val1 != -1)
> > > > + newval = ((newval & 0xfff0) | ((val1/200)&0xf) << 0);
> > > > +
> > > > + if (val2 != -1)
> > > > + newval = ((newval & 0xff0f) | ((val2/200)&0xf) << 4);
> > > > +
> > > > + if (val3 != -1)
> > > > + newval = ((newval & 0xf0ff) | ((val3/200)&0xf) << 8);
> > > > +
> > > > + if (val4 != -1)
> > > > + newval = ((newval & 0x0fff) | ((val4/200)&0xf) << 12);
> > > > +
> > > > + return kszphy_extended_write(phydev, reg, newval); }
> > > > +
> > > > +static int ksz9021_config_init(struct phy_device *phydev) {
> > > > +struct device *dev = &phydev->dev;  struct device_node *of_node =
> > > > +dev->of_node;
> > > > +
> > > > + if (!of_node && dev->parent->of_node) of_node =
> > > > + dev->parent->of_node;
> > > > +
> > > > + if (of_node) {
> > > > + ksz9021_load_values_from_of(phydev, of_node,
> > > > + MII_KSZPHY_CLK_CONTROL_PAD_SKEW, "txen-skew", "txc-skew",
> > > > + "rxdv-skew", "rxc-skew"); ksz9021_load_values_from_of(phydev,
> > > > + of_node, MII_KSZPHY_RX_DATA_PAD_SKEW, "rxd0-skew", "rxd1-skew",
> > > > + "rxd2-skew", "rxd3-skew"); ksz9021_load_values_from_of(phydev,
> > > > + of_node, MII_KSZPHY_TX_DATA_PAD_SKEW, "txd0-skew", "txd1-skew",
> > > > + "txd2-skew", "txd3-skew");
> > >
> > >
> > >
> > >
> > >
> > > Are you sure this register exists? It's not mentioned in my
> > > datasheet, only the first two are.
> >
> >
> >
> > I'm very sure the register exists. There's a hole in the documentation
> where the TX control register should exist. Furthermore, we measured that
> changing values in this register adjusted the TX skew on the RG-MII wires,
> and on our board at least, adjusting these values yields increased
> performance.
> There hasn't been any response to this patch in two weeks.  Can someone
> please merge this patch or indicate what's wrong with it?
>