Commit 9c0770ea authored by Phil Elwell's avatar Phil Elwell Committed by popcornmix
Browse files

net: bcmgenet: Workaround for Pi 4B network issue 

Some combinations of Pi 4Bs and Ethernet switches don't reliably get a
DCHP-assigned IP address, leaving the unit with a self=assigned 169.254
address.

Forcing renegotiation has been found to be an effective workaround, so
add an automatic renegotiation after the link comes up for the first
time; enable it with genet.force_reneg=y - by default it is disabled.

See: https://github.com/raspberrypi/linux/issues/3108



Signed-off-by: default avatarPhil Elwell <phil@raspberrypi.org>
parent a08305b0

drivers/net/ethernet/broadcom/genet/bcmgenet.c

+22 −0
Original line number Diff line number Diff line
@@ -72,6 +72,10 @@ 
#define GENET_RDMA_REG_OFF	(priv->hw_params->rdma_offset + \

				TOTAL_DESC * DMA_DESC_SIZE)



static bool force_reneg = false;

module_param(force_reneg, bool, 0444);

MODULE_PARM_DESC(force_reneg, "Force a renegotiation after the initial link-up");



static inline void bcmgenet_writel(u32 value, void __iomem *offset)

{

	/* MIPS chips strapped for BE will automagically configure the
@@ -2610,6 +2614,7 @@ static void bcmgenet_irq_task(struct work_struct *work) 
	unsigned int status;

	struct bcmgenet_priv *priv = container_of(

			work, struct bcmgenet_priv, bcmgenet_irq_work);

	static int first_link = 1;



	netif_dbg(priv, intr, priv->dev, "%s\n", __func__);
@@ -2622,6 +2627,23 @@ static void bcmgenet_irq_task(struct work_struct *work) 
	if (status & UMAC_IRQ_LINK_EVENT) {

		priv->dev->phydev->link = !!(status & UMAC_IRQ_LINK_UP);

		phy_mac_interrupt(priv->dev->phydev);



		if (priv->dev->phydev->link && first_link) {

			first_link = 0;

			/*

			 * HACK: Some Pi4Bs, when paired with some switches,

			 * come up in a strange state where they are unable to

			 * transmit, causing them to fail to get an IP address.

			 * Although the failure mechanism is not yet understood,

			 * forcing renegotiation at this point has been shown

			 * to be effective in avoiding the problem.

			 */

			if (force_reneg) {

				dev_info(&priv->pdev->dev,

					 "Forcing renegotiation\n");

				genphy_restart_aneg(priv->dev->phydev);

			}

		}

	}

}