linux-kernel - [PATCH 5.15 792/846] net: axienet: Wait for PhyRstCmplt after core reset

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Message-Id: <20220124184128.274931321@linuxfoundation.org>
Date:   Mon, 24 Jan 2022 19:45:09 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Robert Hancock <robert.hancock@...ian.com>,
        Andrew Lunn <andrew@...n.ch>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.15 792/846] net: axienet: Wait for PhyRstCmplt after core reset

From: Robert Hancock <robert.hancock@...ian.com>

commit b400c2f4f4c53c86594dd57098970d97d488bfde upstream.

When resetting the device, wait for the PhyRstCmplt bit to be set
in the interrupt status register before continuing initialization, to
ensure that the core is actually ready. When using an external PHY, this
also ensures we do not start trying to access the PHY while it is still
in reset. The PHY reset is initiated by the core reset which is
triggered just above, but remains asserted for 5ms after the core is
reset according to the documentation.

The MgtRdy bit could also be waited for, but unfortunately when using
7-series devices, the bit does not appear to work as documented (it
seems to behave as some sort of link state indication and not just an
indication the transceiver is ready) so it can't really be relied on for
this purpose.

Fixes: 8a3b7a252dca9 ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver")
Signed-off-by: Robert Hancock <robert.hancock@...ian.com>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -516,6 +516,16 @@ static int __axienet_device_reset(struct
 		return ret;
 	}

+	/* Wait for PhyRstCmplt bit to be set, indicating the PHY reset has finished */
+	ret = read_poll_timeout(axienet_ior, value,
+				value & XAE_INT_PHYRSTCMPLT_MASK,
+				DELAY_OF_ONE_MILLISEC, 50000, false, lp,
+				XAE_IS_OFFSET);
+	if (ret) {
+		dev_err(lp->dev, "%s: timeout waiting for PhyRstCmplt\n", __func__);
+		return ret;
+	}
+
 	return 0;
 }