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

[Patrice CHOTARD]

Hi Daniil

+Christophe

Thanks
Patrice

On 5/24/21 12:24 AM, Daniil Stas 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__);
>