netdev - [RFC 06/19] staging: qlge: disable flow control by default

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Date:   Mon, 21 Jun 2021 21:48:49 +0800
From:   Coiby Xu <coiby.xu@...il.com>
To:     linux-staging@...ts.linux.dev
Cc:     netdev@...r.kernel.org,
        Benjamin Poirier <benjamin.poirier@...il.com>,
        Shung-Hsi Yu <shung-hsi.yu@...e.com>,
        Manish Chopra <manishc@...vell.com>,
        GR-Linux-NIC-Dev@...vell.com (supporter:QLOGIC QLGE 10Gb ETHERNET
        DRIVER), Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org (open list)
Subject: [RFC 06/19] staging: qlge: disable flow control by default

According to the TODO item,
> * the flow control implementation in firmware is buggy (sends a flood of pause
>   frames, resets the link, device and driver buffer queues become
>   desynchronized), disable it by default

Currently, qlge_mpi_port_cfg_work calls qlge_mb_get_port_cfg which gets
the link config from the firmware and saves it to qdev->link_config. By
default, flow control is enabled. This commit writes the
save the pause parameter of qdev->link_config and don't let it
overwritten by link settings of current port. Since qdev->link_config=0
when qdev is initialized, this could disable flow control by default and
the pause parameter value could also survive MPI resetting,
    $ ethtool -a enp94s0f0
    Pause parameters for enp94s0f0:
    Autonegotiate:  off
    RX:             off
    TX:             off

The follow control can be enabled manually,

    $ ethtool -A enp94s0f0 rx on tx on
    $ ethtool -a enp94s0f0
    Pause parameters for enp94s0f0:
    Autonegotiate:  off
    RX:             on
    TX:             on

Signed-off-by: Coiby Xu <coiby.xu@...il.com>
---
 drivers/staging/qlge/TODO       |  3 ---
 drivers/staging/qlge/qlge_mpi.c | 11 ++++++++++-
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/qlge/TODO b/drivers/staging/qlge/TODO
index b7a60425fcd2..8c84160b5993 100644
--- a/drivers/staging/qlge/TODO
+++ b/drivers/staging/qlge/TODO
@@ -4,9 +4,6 @@
   ql_build_rx_skb(). That function is now used exclusively to handle packets
   that underwent header splitting but it still contains code to handle non
   split cases.
-* the flow control implementation in firmware is buggy (sends a flood of pause
-  frames, resets the link, device and driver buffer queues become
-  desynchronized), disable it by default
 * some structures are initialized redundantly (ex. memset 0 after
   alloc_etherdev())
 * the driver has a habit of using runtime checks where compile time checks are
diff --git a/drivers/staging/qlge/qlge_mpi.c b/drivers/staging/qlge/qlge_mpi.c
index 2630ebf50341..0f1c7da80413 100644
--- a/drivers/staging/qlge/qlge_mpi.c
+++ b/drivers/staging/qlge/qlge_mpi.c
@@ -806,6 +806,7 @@ int qlge_mb_get_port_cfg(struct qlge_adapter *qdev)
 {
 	struct mbox_params mbc;
 	struct mbox_params *mbcp = &mbc;
+	u32 saved_pause_link_config = 0;
 	int status = 0;
 
 	memset(mbcp, 0, sizeof(struct mbox_params));
@@ -826,7 +827,15 @@ int qlge_mb_get_port_cfg(struct qlge_adapter *qdev)
 	} else	{
 		netif_printk(qdev, drv, KERN_DEBUG, qdev->ndev,
 			     "Passed Get Port Configuration.\n");
-		qdev->link_config = mbcp->mbox_out[1];
+		/*
+		 * Don't let the pause parameter be overwritten by
+		 *
+		 * In this way, follow control can be disabled by default
+		 * and the setting could also survive the MPI reset
+		 */
+		saved_pause_link_config = qdev->link_config & CFG_PAUSE_STD;
+		qdev->link_config = ~CFG_PAUSE_STD & mbcp->mbox_out[1];
+		qdev->link_config |= saved_pause_link_config;
 		qdev->max_frame_size = mbcp->mbox_out[2];
 	}
 	return status;
-- 
2.32.0