linux-kernel - Re: [PATCH] net: phy: at803x: Request 'reset' GPIO only for AT8030 PHY

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Message-ID: <56F3B9A2.9060801@laposte.net>
Date:	Thu, 24 Mar 2016 10:55:46 +0100
From:	Sebastian Frias <sf84@...oste.net>
To:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>
CC:	Daniel Mack <daniel@...que.org>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	lkml <linux-kernel@...r.kernel.org>, mason <slash.tmp@...e.fr>,
	Florian Fainelli <f.fainelli@...il.com>,
	Mans Rullgard <mans@...sr.com>,
	Fabio Estevam <festevam@...il.com>,
	Martin Blumenstingl <martin.blumenstingl@...il.com>,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH] net: phy: at803x: Request 'reset' GPIO only for AT8030
 PHY

Hi Sergei,

On 03/23/2016 08:42 PM, Sergei Shtylyov wrote:
> Hello.
> 
> On 03/23/2016 01:49 PM, Sebastian Frias wrote:
> 
>> This removes the dependency on GPIOLIB for non faulty PHYs.
>>
>> Indeed, without this patch, if GPIOLIB is not selected
>> devm_gpiod_get_optional() will return -ENOSYS and the driver probe
>> call will fail, regardless of the actual PHY hardware.
>>
>> Out of the 3 PHYs supported by this driver (AT8030, AT8031, AT8035),
>> only AT8030 presents the issues that commit 13a56b449325 ("net: phy:
>> at803x: Add support for hardware reset") attempts to work-around by
>> using a 'reset' GPIO line.
>>
>> Hence, only AT8030 should depend on GPIOLIB operating properly.
>>
>> Fixes: 13a56b449325 ("net: phy: at803x: Add support for hardware reset")
>>
>> Signed-off-by: Sebastian Frias <sf84@...oste.net>
> [...]
> 
>    What I don't understand is why the link_change_notify() method ptr is
> populated for all 3 supported chips while only being needed on 8030...

You are right.
I had commented on that here
https://marc.info/?l=linux-netdev&m=145856582932498&w=2

<quote>
Furthermore, I think we should not even register the
"link_change_notify" callback when dealing with AT803x PHYs that do not
require the hack.
Another solution (considering the callback is statically registered in
the "phy_driver" structs for all AT803x PHYs) would be for the callback
to disable itself.
</quote>

I was waiting for comments from the original implementor.

However, I guess we can remove them as well.
I will make another patch.

Best regards,

Sebastian