netdev - Re: [PATCH v2] net: ethernet: support "fixed-link" DT key/node on nb8800 driver

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Date:	Fri, 05 Feb 2016 15:08:04 +0100
From:	Sebastian Frias <sf84@...oste.net>
To:	Måns Rullgård <mans@...sr.com>
CC:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>, mason <slash.tmp@...e.fr>
Subject: Re: [PATCH v2] net: ethernet: support "fixed-link" DT key/node on
 nb8800 driver

On 02/05/2016 02:58 PM, Måns Rullgård wrote:
> Sebastian Frias <sf84@...oste.net> writes:
>
>> Signed-off-by: Sebastian Frias <sf84@...oste.net>
>> ---
>>   drivers/net/ethernet/aurora/nb8800.c | 15 ++++++++++++---
>>   1 file changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/aurora/nb8800.c
>> b/drivers/net/ethernet/aurora/nb8800.c
>> index ecc4a33..dd7bedc 100644
>> --- a/drivers/net/ethernet/aurora/nb8800.c
>> +++ b/drivers/net/ethernet/aurora/nb8800.c
>> @@ -1462,9 +1462,18 @@ static int nb8800_probe(struct platform_device *pdev)
>>
>>   	priv->phy_node = of_parse_phandle(pdev->dev.of_node, "phy-handle", 0);
>>   	if (!priv->phy_node) {
>> -		dev_err(&pdev->dev, "no PHY specified\n");
>> -		ret = -ENODEV;
>> -		goto err_free_bus;
>> +		if (of_phy_is_fixed_link(pdev->dev.of_node)) {
>> +			ret = of_phy_register_fixed_link(pdev->dev.of_node);
>> +			if (ret < 0) {
>> +				dev_err(&pdev->dev, "bad fixed-link spec\n");
>> +				goto err_free_bus;
>> +			}
>> +			priv->phy_node = of_node_get(pdev->dev.of_node);
>> +		} else {
>> +			dev_err(&pdev->dev, "no PHY specified\n");
>> +			ret = -ENODEV;
>> +			goto err_free_bus;
>> +		}
>>   	}
>
> Maybe it would be clearer to reduce the if() nesting a bit, like this
> for instance:
>
> 	if (of_phy_is_fixed_link(pdev->dev.of_node)) {
> 		ret = of_phy_register_fixed_link(pdev->dev.of_node);
> 		if (ret < 0) {
> 			dev_err(&pdev->dev, "bad fixed-link spec\n");
> 			goto err_free_bus;
> 		}
> 		priv->phy_node = of_node_get(pdev->dev.of_node);
> 	}
>
> 	if (!priv->phy_node)
> 		priv->phy_node = of_parse_phandle(pdev->dev.of_node,
> 						  "phy-handle", 0);
>
> 	if (!priv->phy_node) {
> 		dev_err(&pdev->dev, "no PHY specified\n");
> 		ret = -ENODEV;
> 		goto err_free_bus;
> 	}
>
>

Thanks Måns for your comments.
With old code + my patch, we only hit 1 comparison in the general case, 
and a 2nd one in "fixed-link" case.
With your suggestion above, it would mean that we hit 3 comparisons all 
the time.
If you are ok with the 3 comparisons, I can post a v3.