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52 lines
1.8 KiB
Diff
52 lines
1.8 KiB
Diff
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From 3c252c9745794d454391f378e7b99a4b4ea4b1c3 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Fri, 9 Aug 2019 08:51:43 +0100
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Subject: [PATCH] net: bcmgenet: Workaround #2 for Pi4 Ethernet fail
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Some combinations of Pi 4Bs and Ethernet switches don't reliably get a
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DCHP-assigned IP address, leaving the unit with a self=assigned 169.254
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address. In the failure case, the Pi is left able to receive packets
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but not send them, suggesting that the MAC<->PHY link is getting into
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a bad state.
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It has been found empirically that skipping a reset step by the genet
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driver prevents the failures. No downsides have been discovered yet,
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and unlike the forced renegotiation it doesn't increase the time to
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get an IP address, so the workaround is enabled by default; add
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genet.skip_umac_reset=n
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to the command line to disable it.
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See: https://github.com/raspberrypi/linux/issues/3108
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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drivers/net/ethernet/broadcom/genet/bcmgenet.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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--- a/drivers/net/ethernet/broadcom/genet/bcmgenet.c
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+++ b/drivers/net/ethernet/broadcom/genet/bcmgenet.c
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@@ -67,6 +67,9 @@
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/* Forward declarations */
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static void bcmgenet_set_rx_mode(struct net_device *dev);
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+static bool skip_umac_reset = true;
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+module_param(skip_umac_reset, bool, 0444);
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+MODULE_PARM_DESC(skip_umac_reset, "Skip UMAC reset step");
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static inline void bcmgenet_writel(u32 value, void __iomem *offset)
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{
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@@ -2491,6 +2494,11 @@ static void reset_umac(struct bcmgenet_p
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bcmgenet_rbuf_ctrl_set(priv, 0);
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udelay(10);
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+ if (skip_umac_reset) {
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+ pr_warn("Skipping UMAC reset\n");
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+ return;
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+ }
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+
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/* issue soft reset and disable MAC while updating its registers */
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bcmgenet_umac_writel(priv, CMD_SW_RESET, UMAC_CMD);
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udelay(2);
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