[PATCH] net: dwc_eth_qos: Fix needless phy auto-negotiation restarts

[Ramon Fried]

On Mon, May 24, 2021 at 1:18 AM Daniil Stas <daniil.stas at posteo.net> wrote:
>
> Disabling clk_ck clock leads to link up status loss in phy, which
> leads to auto-negotiation restart before each network command
> execution.
>
> This issue is especially big for PXE boot protocol because of
> auto-negotiation restarts before each configuration filename trial.
>
> To avoid this issue don't disable clk_ck clock after it was enabled.
>
> Signed-off-by: Daniil Stas <daniil.stas at posteo.net>
> Cc: Ramon Fried <rfried.dev at gmail.com>
> Cc: Joe Hershberger <joe.hershberger at ni.com>
> Cc: Patrick Delaunay <patrick.delaunay at foss.st.com>
> Cc: Patrice Chotard <patrice.chotard at foss.st.com>
> ---
>  drivers/net/dwc_eth_qos.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/dwc_eth_qos.c b/drivers/net/dwc_eth_qos.c
> index e8242ca4e1..2f088c758f 100644
> --- a/drivers/net/dwc_eth_qos.c
> +++ b/drivers/net/dwc_eth_qos.c
> @@ -321,6 +321,7 @@ struct eqos_priv {
>         void *rx_pkt;
>         bool started;
>         bool reg_access_ok;
> +       bool clk_ck_enabled;
>  };
>
>  /*
> @@ -591,12 +592,13 @@ static int eqos_start_clks_stm32(struct udevice *dev)
>                 goto err_disable_clk_rx;
>         }
>
> -       if (clk_valid(&eqos->clk_ck)) {
> +       if (clk_valid(&eqos->clk_ck) && !eqos->clk_ck_enabled) {
>                 ret = clk_enable(&eqos->clk_ck);
>                 if (ret < 0) {
>                         pr_err("clk_enable(clk_ck) failed: %d", ret);
>                         goto err_disable_clk_tx;
>                 }
> +               eqos->clk_ck_enabled = true;
>         }
>  #endif
>
> @@ -648,8 +650,6 @@ static void eqos_stop_clks_stm32(struct udevice *dev)
>         clk_disable(&eqos->clk_tx);
>         clk_disable(&eqos->clk_rx);
>         clk_disable(&eqos->clk_master_bus);
> -       if (clk_valid(&eqos->clk_ck))
> -               clk_disable(&eqos->clk_ck);
>  #endif
>
>         debug("%s: OK\n", __func__);
> --
> 2.31.0
>
Reviewed-by: Ramon Fried <rfried.dev at gmail.com >