> -----Original Message-----
> From: Russell King <linux@xxxxxxxxxxxxxxx>
> Sent: Wednesday, January 12, 2022 9:13 PM
> To: Ismail, Mohammad Athari <mohammad.athari.ismail@xxxxxxxxx>
> Cc: Andrew Lunn <andrew@xxxxxxx>; David S . Miller
> <davem@xxxxxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Oleksij
> Rempel <linux@xxxxxxxxxxxxxxxx>; Heiner Kallweit
> <hkallweit1@xxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH net v2] net: phy: marvell: add Marvell specific PHY
> loopback
>
> On Wed, Jan 12, 2022 at 05:33:44PM +0800, Mohammad Athari Bin Ismail
> wrote:
> > +static int marvell_loopback(struct phy_device *phydev, bool enable) {
> > + if (enable) {
> > + u16 bmcr_ctl = 0, mscr2_ctl = 0;
> > +
> > + if (phydev->speed == SPEED_1000)
> > + bmcr_ctl = BMCR_SPEED1000;
> > + else if (phydev->speed == SPEED_100)
> > + bmcr_ctl = BMCR_SPEED100;
> > +
> > + if (phydev->duplex == DUPLEX_FULL)
> > + bmcr_ctl |= BMCR_FULLDPLX;
> > +
> > + phy_modify(phydev, MII_BMCR, ~0, bmcr_ctl);
>
> Is there any point in doing a read-modify-write here if you're just setting all
> bits in the register? Wouldn't phy_write() be more appropriate? What about
> error handing?
Yes, you're right. phy_write() is more suitable. And will add error handling as well.
Will include them in v3 patch.
>
> > +
> > + if (phydev->speed == SPEED_1000)
> > + mscr2_ctl = BMCR_SPEED1000;
> > + else if (phydev->speed == SPEED_100)
> > + mscr2_ctl = BMCR_SPEED100;
> > +
> > + phy_modify_paged(phydev, MII_MARVELL_MSCR_PAGE,
> > + MII_88E1510_MSCR_2, BMCR_SPEED1000 |
> > + BMCR_SPEED100, mscr2_ctl);
> > +
I believe this also need error handling.
> > + /* Need soft reset to have speed configuration takes effect
> */
> > + genphy_soft_reset(phydev);
Ditto.
> > +
> > + /* FIXME: Based on trial and error test, it seem 1G need to
> have
> > + * delay between soft reset and loopback enablement.
> > + */
> > + if (phydev->speed == SPEED_1000)
> > + msleep(1000);
> > +
> > + return phy_modify(phydev, MII_BMCR, BMCR_LOOPBACK,
> > + BMCR_LOOPBACK);
> > + } else {
> > + phy_modify(phydev, MII_BMCR, BMCR_LOOPBACK, 0);
>
> Error handling?
Will add it in v3 patch.
-Athari-
>
> Thanks.
>
> --
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