> -----Original Message-----
> From: Russell King <linux@xxxxxxxxxxxxxxx>
> Sent: Tuesday, September 19, 2023 3:22 PM
> To: Pandey, Radhey Shyam <radhey.shyam.pandey@xxxxxxx>
> Cc: davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx;
> pabeni@xxxxxxxxxx; robh+dt@xxxxxxxxxx;
> krzysztof.kozlowski+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx; Simek, Michal
> <michal.simek@xxxxxxx>; netdev@xxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; git (AMD-Xilinx) <git@xxxxxxx>; Sarath Babu
> Naidu Gaddam <sarath.babu.naidu.gaddam@xxxxxxx>
> Subject: Re: [PATCH net-next v6 2/3] net: axienet: Preparatory changes for
> dmaengine support
>
> On Tue, Sep 19, 2023 at 12:46:54AM +0530, Radhey Shyam Pandey wrote:
> > +/**
> > + * axienet_open - Driver open routine.
> > + * @ndev: Pointer to net_device structure
> > + *
> > + * Return: 0, on success.
> > + * non-zero error value on failure
> > + *
> > + * This is the driver open routine. It calls phylink_start to start
> > +the
> > + * PHY device.
> > + * It also allocates interrupt service routines, enables the
> > +interrupt lines
> > + * and ISR handling. Axi Ethernet core is reset through Axi DMA core.
> > +Buffer
> > + * descriptors are initialized.
> > + */
> > +static int axienet_open(struct net_device *ndev) {
> > + int ret;
> > + struct axienet_local *lp = netdev_priv(ndev);
> > +
> > + dev_dbg(&ndev->dev, "%s\n", __func__);
> > +
> > + /* When we do an Axi Ethernet reset, it resets the complete core
> > + * including the MDIO. MDIO must be disabled before resetting.
> > + * Hold MDIO bus lock to avoid MDIO accesses during the reset.
> > + */
> > + axienet_lock_mii(lp);
> > + ret = axienet_device_reset(ndev);
> > + axienet_unlock_mii(lp);
> > +
> > + ret = phylink_of_phy_connect(lp->phylink, lp->dev->of_node, 0);
> > + if (ret) {
> > + dev_err(lp->dev, "phylink_of_phy_connect() failed: %d\n",
> ret);
> > + return ret;
> > + }
> > +
> > + phylink_start(lp->phylink);
>
> ... and at this point, the link can come up while phylink_start() is completing.
> Could that cause a problem if this happens before:
This preparatory patch keeps same execution sequence and it only
creates wrapper around dma specific initialization. No functional
change.
There shouldn't be any problem if link come up while phylink_start is
completing. Packet will be processed only after dma initialization
(Interrupts are enabled) .
>
> > +
> > + if (!lp->use_dmaengine) {
> > + ret = axienet_init_legacy_dma(ndev);
> > + if (ret)
> > + goto error_code;
> > + }
>
> ?
>
> I suppose I should add this statement to the phylink_start() documentation
> so that this point is clear for everyone.
Seems to be a good idea to capture it in documentation.
>
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
