linux-kernel - Re: [PATCH] mdio_bus: suppress err message for reset gpio EPROBE

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Date:   Thu, 19 Nov 2020 15:38:27 +0200
From:   Grygorii Strashko <grygorii.strashko@...com>
To:     Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>, <netdev@...r.kernel.org>,
        Jakub Kicinski <kuba@...nel.org>, Andrew Lunn <andrew@...n.ch>
CC:     <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mdio_bus: suppress err message for reset gpio
 EPROBE_DEFER



On 19/11/2020 14:30, Heiner Kallweit wrote:
> Am 18.11.2020 um 15:24 schrieb Grygorii Strashko:
>> The mdio_bus may have dependencies from GPIO controller and so got
>> deferred. Now it will print error message every time -EPROBE_DEFER is
>> returned from:
>> __mdiobus_register()
>>   |-devm_gpiod_get_optional()
>> without actually identifying error code.
>>
>> "mdio_bus 4a101000.mdio: mii_bus 4a101000.mdio couldn't get reset GPIO"
>>
>> Hence, suppress error message when devm_gpiod_get_optional() returning
>> -EPROBE_DEFER case.
>>
>> Signed-off-by: Grygorii Strashko <grygorii.strashko@...com>
>> ---
>>   drivers/net/phy/mdio_bus.c | 7 ++++---
>>   1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
>> index 757e950fb745..54fc13043656 100644
>> --- a/drivers/net/phy/mdio_bus.c
>> +++ b/drivers/net/phy/mdio_bus.c
>> @@ -546,10 +546,11 @@ int __mdiobus_register(struct mii_bus *bus, struct module *owner)
>>   	/* de-assert bus level PHY GPIO reset */
>>   	gpiod = devm_gpiod_get_optional(&bus->dev, "reset", GPIOD_OUT_LOW);
>>   	if (IS_ERR(gpiod)) {
>> -		dev_err(&bus->dev, "mii_bus %s couldn't get reset GPIO\n",
>> -			bus->id);
>> +		err = PTR_ERR(gpiod);
>> +		if (err != -EPROBE_DEFER)
>> +			dev_err(&bus->dev, "mii_bus %s couldn't get reset GPIO %d\n", bus->id, err);
>>   		device_del(&bus->dev);
>> -		return PTR_ERR(gpiod);
>> +		return err;
>>   	} else	if (gpiod) {
>>   		bus->reset_gpiod = gpiod;
>>   
>>
> 
> Using dev_err_probe() here would simplify the code.
> 

this was my first though, but was not sure if it's correct as dev_err_probe() will use dev
to store defer reason, but the same 'dev' is deleted on the next line.

I also thought about using bus->parent, but it's not always provided.

So, if you think dev_err_probe(0) can be used - I can change and re-send.

-- 
Best regards,
grygorii