netdev - Re: [PATCH] net: ethernet: fec: Replace interrupt driven MDIO with polled IO

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Date:   Wed, 21 Oct 2020 15:37:58 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Greg Ungerer <gerg@...ux-m68k.org>
Cc:     Chris Heally <cphealy@...il.com>, netdev@...r.kernel.org,
        Fugang Duan <fugang.duan@....com>
Subject: Re: [PATCH] net: ethernet: fec: Replace interrupt driven MDIO with
 polled IO

> +	if (fep->quirks & FEC_QUIRK_CLEAR_SETUP_MII) {
> +		/* Clear MMFR to avoid to generate MII event by writing MSCR.
> +		 * MII event generation condition:
> +		 * - writing MSCR:
> +		 *	- mmfr[31:0]_not_zero & mscr[7:0]_is_zero &
> +		 *	  mscr_reg_data_in[7:0] != 0
> +		 * - writing MMFR:
> +		 *	- mscr[7:0]_not_zero
> +		 */
> +		writel(0, fep->hwp + FEC_MII_DATA);
> +	}

Hi Greg

The last time we discussed this, we decided that if you cannot do the
quirk, you need to wait around for an MDIO interrupt, e.g. call
fec_enet_mdio_wait() after setting FEC_MII_SPEED register.

>  
>  	writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED);

	Andrew