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Message-ID: <ZRwTwd18xWczDnur@shell.armlinux.org.uk>
Date: Tue, 3 Oct 2023 14:14:41 +0100
From: "Russell King (Oracle)" <linux@...linux.org.uk>
To: Vladimir Oltean <vladimir.oltean@....com>
Cc: netdev@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-phy@...ts.infradead.org,
Heiner Kallweit <hkallweit1@...il.com>,
Andrew Lunn <andrew@...n.ch>,
Florian Fainelli <f.fainelli@...il.com>,
Madalin Bucur <madalin.bucur@....com>,
Ioana Ciornei <ioana.ciornei@....com>,
Camelia Groza <camelia.groza@....com>,
Li Yang <leoyang.li@....com>, Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor@...nel.org>,
Sean Anderson <sean.anderson@...o.com>,
Maxime Chevallier <maxime.chevallier@...tlin.com>,
Vinod Koul <vkoul@...nel.org>,
Kishon Vijay Abraham I <kishon@...nel.org>
Subject: Re: [RFC PATCH v2 net-next 15/15] net: pcs: lynx: use MTIP AN/LT
block for copper backplanes
On Sat, Sep 23, 2023 at 04:49:04PM +0300, Vladimir Oltean wrote:
> +static int lynx_pcs_parse_fwnode(struct lynx_pcs *lynx)
> +{
> + struct fwnode_handle *node = lynx->mdio->dev.fwnode;
> + enum mtip_model model = MTIP_MODEL_AUTODETECT;
> + struct device_node *np = to_of_node(node);
> + struct mdio_device *mdio = lynx->mdio;
> + struct device *dev = &mdio->dev;
> + struct phy *phy;
> + int i, err;
> +
> + if (!node)
> + return 0;
> +
> + lynx->backplane_mode = fwnode_property_present(node, "fsl,backplane-mode");
> + if (!lynx->backplane_mode)
> + return 0;
> +
> + if (fwnode_device_is_compatible(node, "fsl,lx2160a-lynx-pcs"))
> + model = MTIP_MODEL_LX2160A;
> +
> + lynx->num_lanes = of_count_phandle_with_args(np, "phys", "#phy-cells");
> + if (lynx->num_lanes < 0)
> + return lynx->num_lanes;
Is it possible for ->num_lanes to be zero at this point? If that is
possible, then ->anlt[PRIMARY_LANE] will be NULL but ->backplane_mode
will be set, so won't that cause the mtip_* calls above to pass a
NULL pointer into those functions? Is that safe? Should we trap that
case here?
If that's correct, then I don't see any point in storing
->backplane_mode, since we can then use ->num_lanes > PRIMARY_LANE
or similar instead.
> +
> + if (WARN_ON(lynx->num_lanes > MAX_NUM_LANES))
> + return -EINVAL;
Do we need to use WARN_ON() here, or would it be better to print a short
error-level message?
> +
> + for (i = 0; i < lynx->num_lanes; i++) {
> + phy = devm_of_phy_get_by_index(dev, np, i);
> + if (IS_ERR(phy))
> + return dev_err_probe(dev, PTR_ERR(phy),
> + "Failed to get SerDes PHY %d\n", i);
> +
> + lynx->anlt[i] = mtip_backplane_create(mdio, phy, model);
> + if (IS_ERR(lynx->anlt[i])) {
> + err = PTR_ERR(lynx->anlt[i]);
> +
> + while (i-- > 0)
> + mtip_backplane_destroy(lynx->anlt[i]);
> +
> + return err;
> + }
> + }
> +
> + for (i = 1; i < lynx->num_lanes; i++) {
> + err = mtip_backplane_add_subordinate(lynx->anlt[PRIMARY_LANE],
> + lynx->anlt[i]);
> + if (WARN_ON(err)) {
Again, does this need to be a backtrace-producing WARN_ON()?
> + /* Too many SerDes lanes in the device tree? */
> + for (i = 0; i < lynx->num_lanes; i++)
> + mtip_backplane_destroy(lynx->anlt[i]);
> + return err;
> + }
> + }
> +
> + return 0;
> +}
> +
> static struct phylink_pcs *lynx_pcs_create(struct mdio_device *mdio)
> {
> struct lynx_pcs *lynx;
> + int err;
>
> lynx = kzalloc(sizeof(*lynx), GFP_KERNEL);
> if (!lynx)
> @@ -327,6 +451,12 @@ static struct phylink_pcs *lynx_pcs_create(struct mdio_device *mdio)
> lynx->pcs.neg_mode = true;
> lynx->pcs.poll = true;
>
> + err = lynx_pcs_parse_fwnode(lynx);
> + if (err) {
> + kfree(lynx);
> + return ERR_PTR(err);
> + }
> +
> return lynx_to_phylink_pcs(lynx);
> }
>
> @@ -392,6 +522,11 @@ EXPORT_SYMBOL_GPL(lynx_pcs_create_fwnode);
> void lynx_pcs_destroy(struct phylink_pcs *pcs)
> {
> struct lynx_pcs *lynx = phylink_pcs_to_lynx(pcs);
> + int i;
> +
> + if (lynx->backplane_mode)
> + for (i = 0; i < lynx->num_lanes; i++)
> + mtip_backplane_destroy(lynx->anlt[i]);
Won't ->num_lanes only be non-zero when ->backplane_mode is set, so
isn't the test for ->backplane_mode redundant here?
>
> mdio_device_put(lynx->mdio);
> kfree(lynx);
> --
> 2.34.1
>
>
--
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