netdev - Re: [PATCH RFC net-next 01/10] net: pcs: xpcs: move PCS reset to .pcs_pre

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Message-ID: <mykeabksgikgk6otbub2i3ksfettbozuhqy3gt5vyezmemvttg@cpjn5bcfiwei>
Date: Mon, 30 Sep 2024 01:16:57 +0300
From: Serge Semin <fancer.lancer@...il.com>
To: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>, 
	Alexandre Torgue <alexandre.torgue@...s.st.com>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Florian Fainelli <f.fainelli@...il.com>, 
	Jakub Kicinski <kuba@...nel.org>, Jiawen Wu <jiawenwu@...stnetic.com>, 
	Jose Abreu <joabreu@...opsys.com>, Jose Abreu <Jose.Abreu@...opsys.com>, 
	linux-arm-kernel@...ts.infradead.org, linux-stm32@...md-mailman.stormreply.com, 
	Maxime Coquelin <mcoquelin.stm32@...il.com>, Mengyuan Lou <mengyuanlou@...-swift.com>, netdev@...r.kernel.org, 
	Paolo Abeni <pabeni@...hat.com>, Vladimir Oltean <olteanv@...il.com>
Subject: Re: [PATCH RFC net-next 01/10] net: pcs: xpcs: move PCS reset to
 .pcs_pre_config()

Hi Russell

On Mon, Sep 23, 2024 at 03:00:59PM GMT, Russell King (Oracle) wrote:
> Move the PCS reset to .pcs_pre_config() rather than at creation time,
> which means we call the reset function with the interface that we're
> actually going to be using to talk to the downstream device.

The PCS-reset procedure actually can be converted to being independent
from the PHY-interface. Thus you won't need to move the PCS resetting
to the pre_config() method, and get rid from the pointer to
dw_xpcs_compat utilization each time the reset is required.
Please see the attached patch for details.*

* I was going to submit it as a part of a one more XPCS-related series,
but seeing my work interfere with yours I'll hold on with sending my
patch set for until yours is merged in.

> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> ---
>  drivers/net/pcs/pcs-xpcs.c   | 39 +++++++++++++++++++++++++++---------
>  include/linux/pcs/pcs-xpcs.h |  1 +
>  2 files changed, 30 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/pcs/pcs-xpcs.c b/drivers/net/pcs/pcs-xpcs.c
> index 82463f9d50c8..7c6c40ddf722 100644
> --- a/drivers/net/pcs/pcs-xpcs.c
> +++ b/drivers/net/pcs/pcs-xpcs.c
> @@ -659,6 +659,30 @@ int xpcs_config_eee(struct dw_xpcs *xpcs, int mult_fact_100ns, int enable)
>  }
>  EXPORT_SYMBOL_GPL(xpcs_config_eee);
>  
> +static void xpcs_pre_config(struct phylink_pcs *pcs, phy_interface_t interface)
> +{
> +	struct dw_xpcs *xpcs = phylink_pcs_to_xpcs(pcs);
> +	const struct dw_xpcs_compat *compat;
> +	int ret;
> +
> +	if (!xpcs->need_reset)
> +		return;
> +

> +	compat = xpcs_find_compat(xpcs->desc, interface);
> +	if (!compat) {
> +		dev_err(&xpcs->mdiodev->dev, "unsupported interface %s\n",
> +			phy_modes(interface));
> +		return;
> +	}

Please note, it's better to preserve the xpcs_find_compat() call even
if the need_reset flag is false, since it makes sure that the
PHY-interface is actually supported by the PCS.

> +
> +	ret = xpcs_soft_reset(xpcs, compat);
> +	if (ret)
> +		dev_err(&xpcs->mdiodev->dev, "soft reset failed: %pe\n",
> +			ERR_PTR(ret));
> +
> +	xpcs->need_reset = false;
> +}
> +
>  static int xpcs_config_aneg_c37_sgmii(struct dw_xpcs *xpcs,
>  				      unsigned int neg_mode)
>  {
> @@ -1365,6 +1389,7 @@ static const struct dw_xpcs_desc xpcs_desc_list[] = {
>  
>  static const struct phylink_pcs_ops xpcs_phylink_ops = {
>  	.pcs_validate = xpcs_validate,
> +	.pcs_pre_config = xpcs_pre_config,
>  	.pcs_config = xpcs_config,
>  	.pcs_get_state = xpcs_get_state,
>  	.pcs_an_restart = xpcs_an_restart,
> @@ -1460,18 +1485,12 @@ static int xpcs_init_id(struct dw_xpcs *xpcs)
>  
>  static int xpcs_init_iface(struct dw_xpcs *xpcs, phy_interface_t interface)
>  {
> -	const struct dw_xpcs_compat *compat;
> -
> -	compat = xpcs_find_compat(xpcs->desc, interface);
> -	if (!compat)
> -		return -EINVAL;
> -
> -	if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID) {
> +	if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID)
>  		xpcs->pcs.poll = false;
> -		return 0;
> -	}
> +	else
> +		xpcs->need_reset = true;
>  
> -	return xpcs_soft_reset(xpcs, compat);
> +	return 0;
>  }
>  
>  static struct dw_xpcs *xpcs_create(struct mdio_device *mdiodev,
> diff --git a/include/linux/pcs/pcs-xpcs.h b/include/linux/pcs/pcs-xpcs.h
> index b4a4eb6c8866..fd75d0605bb6 100644
> --- a/include/linux/pcs/pcs-xpcs.h
> +++ b/include/linux/pcs/pcs-xpcs.h
> @@ -61,6 +61,7 @@ struct dw_xpcs {
>  	struct clk_bulk_data clks[DW_XPCS_NUM_CLKS];
>  	struct phylink_pcs pcs;
>  	phy_interface_t interface;

> +	bool need_reset;

If you still prefer the PCS-reset being done in the pre_config()
function, then what about just directly checking the PMA id in there?

	if (xpcs->info.pma == WX_TXGBE_XPCS_PMA_10G_ID)
		return 0;

	return xpcs_soft_reset(xpcs);

-Serge(y)

>  };
>  
>  int xpcs_get_an_mode(struct dw_xpcs *xpcs, phy_interface_t interface);
> -- 
> 2.30.2
> 
> 

View attachment "0001-net-pcs-xpcs-Drop-compat-arg-from-soft-reset-method.patch" of type "text/x-patch" (4917 bytes)