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

Benjamin Poirier
2021-06-22T07:49:59Z

On 2021-06-21 21:48 +0800, Coiby Xu wrote:
> 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@gmail.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;

Initialization is not needed given the code below, in fact the
declaration can be moved to the block below.

> 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
> + */

It seems this comment is incomplete. Also, it's "flow control", not
"follow control".

> + 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
>