Re: [PATCH] net: fec: fix enet_out clock handling

[Michael Heimpold]

Hi,

Am 27.11.2015 um 14:39 schrieb Lothar WaÃmann:
> When ENET_OUT is being used as reference clock for an external PHY,
> the clock must not be disabled while the PHY is active. Otherwise the
> PHY may lose its internal state and require a reset to become
> functional again.
>
> A symptom for this bug is a network interface that constantly toggles
> between UP and DOWN state:
> fec 800f0000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
> fec 800f0000.ethernet eth0: Link is Down
> fec 800f0000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
> fec 800f0000.ethernet eth0: Link is Down
> [...]

I would add a sentence about the solution, e.g. moving ENET_OUT handling to driver probe etc.

> Signed-off-by: Lothar WaÃmann <LW@xxxxxxxxxxxxxxxxxxx>
> ---
>   drivers/net/ethernet/freescale/fec_main.c | 34 +++++++++++++------------------
>   1 file changed, 14 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
> index d2328fc..d9df4c5 100644
> --- a/drivers/net/ethernet/freescale/fec_main.c
> +++ b/drivers/net/ethernet/freescale/fec_main.c
> @@ -1857,11 +1857,6 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
>   		ret = clk_prepare_enable(fep->clk_ahb);
>   		if (ret)
>   			return ret;
> -		if (fep->clk_enet_out) {
> -			ret = clk_prepare_enable(fep->clk_enet_out);
> -			if (ret)
> -				goto failed_clk_enet_out;
> -		}
>   		if (fep->clk_ptp) {
>   			mutex_lock(&fep->ptp_clk_mutex);
>   			ret = clk_prepare_enable(fep->clk_ptp);
> @@ -1873,35 +1868,26 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
>   			}
>   			mutex_unlock(&fep->ptp_clk_mutex);
>   		}
> -		if (fep->clk_ref) {
> -			ret = clk_prepare_enable(fep->clk_ref);
> -			if (ret)
> -				goto failed_clk_ref;
> -		}
> +		ret = clk_prepare_enable(fep->clk_ref);
> +		if (ret)
> +			goto failed_clk_ref;

This change seems unrelated to the problem. At least, I can leave this part out
and the toggle still disappear after apply the remaining parts.
However, I've only my Duckbill (iMX28) around to test with.

>   	} else {
>   		clk_disable_unprepare(fep->clk_ahb);
> -		if (fep->clk_enet_out)
> -			clk_disable_unprepare(fep->clk_enet_out);
>   		if (fep->clk_ptp) {
>   			mutex_lock(&fep->ptp_clk_mutex);
>   			clk_disable_unprepare(fep->clk_ptp);
>   			fep->ptp_clk_on = false;
>   			mutex_unlock(&fep->ptp_clk_mutex);
>   		}
> -		if (fep->clk_ref)
> -			clk_disable_unprepare(fep->clk_ref);
> +		clk_disable_unprepare(fep->clk_ref);

Same as above, might be unrelated.

>   	}
>   
>   	return 0;
>   
>   failed_clk_ref:
> -	if (fep->clk_ref)
> -		clk_disable_unprepare(fep->clk_ref);
> +	clk_disable_unprepare(fep->clk_ref);
dito

>   failed_clk_ptp:
> -	if (fep->clk_enet_out)
> -		clk_disable_unprepare(fep->clk_enet_out);
> -failed_clk_enet_out:
> -		clk_disable_unprepare(fep->clk_ahb);
> +	clk_disable_unprepare(fep->clk_ahb);
>   
>   	return ret;
>   }
> @@ -3425,6 +3411,10 @@ fec_probe(struct platform_device *pdev)
>   	if (ret)
>   		goto failed_clk;
>   
> +	ret = clk_prepare_enable(fep->clk_enet_out);
> +	if (ret)
> +		goto failed_clk_enet_out;
> +
As enet_out is optional, shouldn't this block be guarded by
if (fep->clk_enet_out)... ?

>   	ret = clk_prepare_enable(fep->clk_ipg);
>   	if (ret)
>   		goto failed_clk_ipg;
> @@ -3509,6 +3499,8 @@ failed_init:
>   	if (fep->reg_phy)
>   		regulator_disable(fep->reg_phy);
>   failed_regulator:
> +	clk_disable_unprepare(fep->clk_enet_out);
here too?
> +failed_clk_enet_out:
>   	clk_disable_unprepare(fep->clk_ipg);
>   failed_clk_ipg:
>   	fec_enet_clk_enable(ndev, false);
> @@ -3531,6 +3523,8 @@ fec_drv_remove(struct platform_device *pdev)
>   	fec_ptp_stop(pdev);
>   	unregister_netdev(ndev);
>   	fec_enet_mii_remove(fep);
> +	fec_enet_clk_enable(ndev, false);
> +	clk_disable_unprepare(fep->clk_enet_out);

and here too?

>   	if (fep->reg_phy)
>   		regulator_disable(fep->reg_phy);
>   	of_node_put(fep->phy_node);

Mit freundlichen GrÃÃen / Kind regards
Michael Heimpold
--
Software Engineer

I2SE GmbH                           Tel: +49 (0) 341 355667-00
Friedrich-Ebert-Str. 61             Fax: +49 (0) 341 355667-02
04109 Leipzig
Germany
Web: http://www.i2se.com/           Mail: info@xxxxxxxx
VAT No.: DE 811528334
Amtsgericht Leipzig HRB 23784
GeschÃftsfÃhrer/CEO: Carsten Ziermann

*** Diese E-Mail ist allein fÃr den bezeichneten Adressaten bestimmt. Sie kann rechtlich vertrauliche Informationen enthalten. Wenn Sie diese E-Mail irrtÃmlich erhalten haben, informieren Sie bitte unverzÃglich den Absender per E-Mail und lÃschen Sie diese E-Mail von Ihrem Computer, ohne Kopien anzufertigen.
Vielen Dank. ***

*** This email is for the exclusive use of the addressee. It may contain legally privileged information. If you have received this message in error, please notify the sender by email immediately and delete the message from your computer without making any copies.
Thank you. ***

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/