linux-kernel - Re: [PATCH] net: phy: at803x: don't depend on GPIOLIB

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Message-ID: <56F26BF7.3090201@laposte.net>
Date:	Wed, 23 Mar 2016 11:12:07 +0100
From:	Sebastian Frias <sf84@...oste.net>
To:	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: don't depend on GPIOLIB

Hi Uwe,

On 03/22/2016 08:42 PM, Uwe Kleine-König wrote:
> Hello Sebastian,
> 
> On Tue, Mar 22, 2016 at 03:34:23PM +0100, Sebastian Frias wrote:
>> I think we are in a deadlock :-)
>> I'm going to reply inline below, but I will also send a different email
>> to Daniel with a small recap.
>> I think he should share the intent of the "reset" mechanism he
>> introduced, in particular if it is mandatory.
> 
> The things I said in my mail are valid in general, not only for the
> at803x phy.
> 
> Let me repeat them once more:
> 
> Preconditions:
>  - Some of the devices a given driver handles have a reset line and
>    others don't.
>  - A non-empty subset (maybe all) of the devices that have a reset line
>    require that this reset line is used.
> 
> Then the way to handle this in the driver should be done as follows:
> 
>   unless reset_handling_not_necessary():
>     gpio = gpiod_get_optional("reset")
>     if IS_ERR(gpio):
>       return PTR_ERR(gpio)
> 
> Checking for -ENOSYS or GPIOLIB=n is not allowed because the device
> you're currently handling might need the GPIO, so you must not continue
> without the ability to control the line.
> 
> So the options you have (as you have a phy that doesn't need the reset
> handling):
> 
>  - enable GPIOLIB (either in your .config or introduce a Kconfig
>    dependency)
>  - improve reset_handling_not_necessary() to return true for your case
> 

I will see if I can "improve reset_handling_not_necessary() to return true".

Best regards,

Sebastian