linux-kernel - Re: [RFC 7/7] net: pcs: Drop the TSE PCS driver

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Message-ID: <20230515114809.d4jzhiazymfqajbj@skbuf>
Date:   Mon, 15 May 2023 14:48:09 +0300
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Maxime Chevallier <maxime.chevallier@...tlin.com>
Cc:     Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        rafael@...nel.org, Colin Foster <colin.foster@...advantage.com>,
        Lee Jones <lee@...nel.org>, davem@...emloft.net,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        thomas.petazzoni@...tlin.com
Subject: Re: [RFC 7/7] net: pcs: Drop the TSE PCS driver

Hi Maxime,

On Fri, Mar 24, 2023 at 10:36:44AM +0100, Maxime Chevallier wrote:
> Now that we can easily create a mdio-device that represents a
> memory-mapped device that exposes an MDIO-like register layout, we don't
> need the Altera TSE PCS anymore, since we can use the Lynx PCS instead.
> 
> Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
> ---
> -static int tse_pcs_reset(struct altera_tse_pcs *tse_pcs)
> -{
> -	u16 bmcr;
> -
> -	/* Reset PCS block */
> -	bmcr = tse_pcs_read(tse_pcs, MII_BMCR);
> -	bmcr |= BMCR_RESET;
> -	tse_pcs_write(tse_pcs, MII_BMCR, bmcr);
> -
> -	return read_poll_timeout(tse_pcs_read, bmcr, (bmcr & BMCR_RESET),
> -				 10, SGMII_PCS_SW_RESET_TIMEOUT, 1,
> -				 tse_pcs, MII_BMCR);
> -}

I just noticed this difference between the Lynx PCS and Altera TSE PCS
drivers. The Lynx driver doesn't reset the PCS, and if it did, it would
wait until the opposite condition from yours would be true: BMCR_RESET
should clear: "!(bmcr & BMCR_RESET)".

Is your reset procedure correct, I wonder?