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    Subject[PATCH 5.6 26/43] net/ethernet/freescale: rework quiesce/activate for ucc_geth
    Date
    From: Valentin Longchamp <valentin@longchamp.me>

    [ Upstream commit 79dde73cf9bcf1dd317a2667f78b758e9fe139ed ]

    ugeth_quiesce/activate are used to halt the controller when there is a
    link change that requires to reconfigure the mac.

    The previous implementation called netif_device_detach(). This however
    causes the initial activation of the netdevice to fail precisely because
    it's detached. For details, see [1].

    A possible workaround was the revert of commit
    net: linkwatch: add check for netdevice being present to linkwatch_do_dev
    However, the check introduced in the above commit is correct and shall be
    kept.

    The netif_device_detach() is thus replaced with
    netif_tx_stop_all_queues() that prevents any tranmission. This allows to
    perform mac config change required by the link change, without detaching
    the corresponding netdevice and thus not preventing its initial
    activation.

    [1] https://lists.openwall.net/netdev/2020/01/08/201

    Signed-off-by: Valentin Longchamp <valentin@longchamp.me>
    Acked-by: Matteo Ghidoni <matteo.ghidoni@ch.abb.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/ethernet/freescale/ucc_geth.c | 13 +++++++------
    1 file changed, 7 insertions(+), 6 deletions(-)

    diff --git a/drivers/net/ethernet/freescale/ucc_geth.c b/drivers/net/ethernet/freescale/ucc_geth.c
    index 0d101c00286f..ab1b4a77b4a3 100644
    --- a/drivers/net/ethernet/freescale/ucc_geth.c
    +++ b/drivers/net/ethernet/freescale/ucc_geth.c
    @@ -42,6 +42,7 @@
    #include <soc/fsl/qe/ucc.h>
    #include <soc/fsl/qe/ucc_fast.h>
    #include <asm/machdep.h>
    +#include <net/sch_generic.h>

    #include "ucc_geth.h"

    @@ -1548,11 +1549,8 @@ static int ugeth_disable(struct ucc_geth_private *ugeth, enum comm_dir mode)

    static void ugeth_quiesce(struct ucc_geth_private *ugeth)
    {
    - /* Prevent any further xmits, plus detach the device. */
    - netif_device_detach(ugeth->ndev);
    -
    - /* Wait for any current xmits to finish. */
    - netif_tx_disable(ugeth->ndev);
    + /* Prevent any further xmits */
    + netif_tx_stop_all_queues(ugeth->ndev);

    /* Disable the interrupt to avoid NAPI rescheduling. */
    disable_irq(ugeth->ug_info->uf_info.irq);
    @@ -1565,7 +1563,10 @@ static void ugeth_activate(struct ucc_geth_private *ugeth)
    {
    napi_enable(&ugeth->napi);
    enable_irq(ugeth->ug_info->uf_info.irq);
    - netif_device_attach(ugeth->ndev);
    +
    + /* allow to xmit again */
    + netif_tx_wake_all_queues(ugeth->ndev);
    + __netdev_watchdog_up(ugeth->ndev);
    }

    /* Called every time the controller might need to be made
    --
    2.25.1


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