linux-kernel - Re: [PATCH 3/3] net: phy: realtek: Support SSC for the RTL8211E

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Message-ID: <20190701221104.GC250418@google.com>
Date:   Mon, 1 Jul 2019 15:11:04 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Andrew Lunn <andrew@...n.ch>,
        Florian Fainelli <f.fainelli@...il.com>,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>
Subject: Re: [PATCH 3/3] net: phy: realtek: Support SSC for the RTL8211E

On Mon, Jul 01, 2019 at 10:49:45PM +0200, Heiner Kallweit wrote:
> On 01.07.2019 21:52, Matthias Kaehlcke wrote:
> > By default Spread-Spectrum Clocking (SSC) is disabled on the RTL8211E.
> > Enable it if the device tree property 'realtek,enable-ssc' exists.
> > 
> > Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> > ---
> >  drivers/net/phy/realtek.c | 27 ++++++++++++++++++++++++---
> >  1 file changed, 24 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/net/phy/realtek.c b/drivers/net/phy/realtek.c
> > index dfc2e20ef335..b617169ccc8c 100644
> > --- a/drivers/net/phy/realtek.c
> > +++ b/drivers/net/phy/realtek.c
> > @@ -9,8 +9,10 @@
> >   * Copyright (c) 2004 Freescale Semiconductor, Inc.
> >   */
> >  #include <linux/bitops.h>
> > -#include <linux/phy.h>
> > +#include <linux/device.h>
> > +#include <linux/of.h>
> >  #include <linux/module.h>
> > +#include <linux/phy.h>
> >  
> >  #define RTL821x_PHYSR				0x11
> >  #define RTL821x_PHYSR_DUPLEX			BIT(13)
> > @@ -28,6 +30,8 @@
> >  
> >  #define RTL8211E_EXT_PAGE			7
> >  #define RTL8211E_EPAGSR				0x1e
> > +#define RTL8211E_SCR				0x1a
> > +#define RTL8211E_SCR_DISABLE_RXC_SSC		BIT(2)
> >  
> >  #define RTL8211F_INSR				0x1d
> >  
> > @@ -87,8 +91,8 @@ static int rtl821e_restore_page(struct phy_device *phydev, int oldpage, int ret)
> >  	return ret;
> >  }
> >  
> > -static int __maybe_unused rtl8211e_modify_ext_paged(struct phy_device *phydev,
> > -				    int page, u32 regnum, u16 mask, u16 set)
> > +static int rtl8211e_modify_ext_paged(struct phy_device *phydev, int page,
> > +				     u32 regnum, u16 mask, u16 set)
> >  {
> >  	int ret = 0;
> >  	int oldpage;
> > @@ -114,6 +118,22 @@ static int __maybe_unused rtl8211e_modify_ext_paged(struct phy_device *phydev,
> >  	return rtl821e_restore_page(phydev, oldpage, ret);
> >  }
> >  
> > +static int rtl8211e_probe(struct phy_device *phydev)
> > +{
> > +	struct device *dev = &phydev->mdio.dev;
> > +	int err;
> > +
> > +	if (of_property_read_bool(dev->of_node, "realtek,enable-ssc")) {
> > +		err = rtl8211e_modify_ext_paged(phydev, 0xa0, RTL8211E_SCR,
> > +						RTL8211E_SCR_DISABLE_RXC_SSC,
> > +						0);
> > +		if (err)
> > +			dev_err(dev, "failed to enable SSC on RXC: %d\n", err);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  static int rtl8201_ack_interrupt(struct phy_device *phydev)
> >  {
> >  	int err;
> > @@ -372,6 +392,7 @@ static struct phy_driver realtek_drvs[] = {
> >  		.config_init	= &rtl8211e_config_init,
> >  		.ack_interrupt	= &rtl821x_ack_interrupt,
> >  		.config_intr	= &rtl8211e_config_intr,
> > +		.probe          = rtl8211e_probe,
> 
> I'm not sure whether this setting survives soft reset and power-down.
> Maybe it should be better applied in the config_init callback.

Sounds reasonable, I'll change it in the next revision, thanks!