linux-kernel - RE: [PATCH] net: fec: Refactor MAC reset to function

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Message-ID:
 <PAXPR04MB851066EBEE8ADBFEBB1407BB88E02@PAXPR04MB8510.eurprd04.prod.outlook.com>
Date: Thu, 23 Jan 2025 01:24:01 +0000
From: Wei Fang <wei.fang@....com>
To: Csókás, Bence <csokas.bence@...lan.hu>, Laurent Badel
	<laurentbadel@...on.com>, Jakub Kicinski <kuba@...nel.org>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
CC: Ahmad Fatoum <a.fatoum@...gutronix.de>, Simon Horman <horms@...nel.org>,
	Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>, Shenwei Wang
	<shenwei.wang@....com>, Clark Wang <xiaoning.wang@....com>, Andrew Lunn
	<andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>, Eric
 Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>
Subject: RE: [PATCH] net: fec: Refactor MAC reset to function

> The core is reset both in `fec_restart()` (called on link-up) and
> `fec_stop()` (going to sleep, driver remove etc.). These two functions
> had their separate implementations, which was at first only a register
> write and a `udelay()` (and the accompanying block comment). However,
> since then we got soft-reset (MAC disable) and Wake-on-LAN support, which
> meant that these implementations diverged, often causing bugs. For
> instance, as of now, `fec_stop()` does not check for
> `FEC_QUIRK_NO_HARD_RESET`, and `fec_restart()` missed the refactor in
> commit ff049886671c ("net: fec: Refactor: #define magic constants")
> renaming the "magic" constant `1` to `FEC_ECR_RESET`.
> 
> To eliminate this bug-source, refactor implementation to a common function.
> 
> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
> Fixes: c730ab423bfa ("net: fec: Fix temporary RMII clock reset on link up")
> Signed-off-by: Csókás, Bence <csokas.bence@...lan.hu>
> ---

You seem to have missed Andrew's comment in the v1. If this patch is just
a refactor, then the Fixes tag should be removed, and the target tree should
be net-next. If not, please describe the bug in more detail in the commit
message.

> 
> Notes:
>     Recommended options for this patch:
>     `--color-moved --color-moved-ws=allow-indentation-change`
>     Changes in v2:
>     * collect Michal's tag
>     * reformat message to 75 cols
>     * fix missing `u32 val`
> 
>  drivers/net/ethernet/freescale/fec_main.c | 52 +++++++++++------------
>  1 file changed, 25 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/fec_main.c
> b/drivers/net/ethernet/freescale/fec_main.c
> index 68725506a095..520fe638ea00 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -1064,6 +1064,29 @@ static void fec_enet_enable_ring(struct net_device
> *ndev)
>  	}
>  }
> 
> +/* Whack a reset.  We should wait for this.
> + * For i.MX6SX SOC, enet use AXI bus, we use disable MAC
> + * instead of reset MAC itself.
> + */
> +static void fec_ctrl_reset(struct fec_enet_private *fep, bool wol)
> +{
> +	u32 val;
> +
> +	if (!wol || !(fep->wol_flag & FEC_WOL_FLAG_SLEEP_ON)) {
> +		if (fep->quirks & FEC_QUIRK_HAS_MULTI_QUEUES ||
> +		    ((fep->quirks & FEC_QUIRK_NO_HARD_RESET) && fep->link)) {
> +			writel(0, fep->hwp + FEC_ECNTRL);
> +		} else {
> +			writel(FEC_ECR_RESET, fep->hwp + FEC_ECNTRL);
> +			udelay(10);
> +		}
> +	} else {
> +		val = readl(fep->hwp + FEC_ECNTRL);
> +		val |= (FEC_ECR_MAGICEN | FEC_ECR_SLEEP);
> +		writel(val, fep->hwp + FEC_ECNTRL);
> +	}
> +}
> +
>  /*
>   * This function is called to start or restart the FEC during a link
>   * change, transmit timeout, or to reconfigure the FEC.  The network
> @@ -1080,17 +1103,7 @@ fec_restart(struct net_device *ndev)
>  	if (fep->bufdesc_ex)
>  		fec_ptp_save_state(fep);
> 
> -	/* Whack a reset.  We should wait for this.
> -	 * For i.MX6SX SOC, enet use AXI bus, we use disable MAC
> -	 * instead of reset MAC itself.
> -	 */
> -	if (fep->quirks & FEC_QUIRK_HAS_MULTI_QUEUES ||
> -	    ((fep->quirks & FEC_QUIRK_NO_HARD_RESET) && fep->link)) {
> -		writel(0, fep->hwp + FEC_ECNTRL);
> -	} else {
> -		writel(1, fep->hwp + FEC_ECNTRL);
> -		udelay(10);
> -	}
> +	fec_ctrl_reset(fep, false);
> 
>  	/*
>  	 * enet-mac reset will reset mac address registers too,
> @@ -1344,22 +1357,7 @@ fec_stop(struct net_device *ndev)
>  	if (fep->bufdesc_ex)
>  		fec_ptp_save_state(fep);
> 
> -	/* Whack a reset.  We should wait for this.
> -	 * For i.MX6SX SOC, enet use AXI bus, we use disable MAC
> -	 * instead of reset MAC itself.
> -	 */
> -	if (!(fep->wol_flag & FEC_WOL_FLAG_SLEEP_ON)) {
> -		if (fep->quirks & FEC_QUIRK_HAS_MULTI_QUEUES) {
> -			writel(0, fep->hwp + FEC_ECNTRL);
> -		} else {
> -			writel(FEC_ECR_RESET, fep->hwp + FEC_ECNTRL);
> -			udelay(10);
> -		}
> -	} else {
> -		val = readl(fep->hwp + FEC_ECNTRL);
> -		val |= (FEC_ECR_MAGICEN | FEC_ECR_SLEEP);
> -		writel(val, fep->hwp + FEC_ECNTRL);
> -	}
> +	fec_ctrl_reset(fep, true);
>  	writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED);
>  	writel(FEC_DEFAULT_IMASK, fep->hwp + FEC_IMASK);
> 
> --
> 2.48.1
>