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From: Linus Walleij <>
To: Michal Simek <>
Cc: "" <>,
	Michal Simek <>,
	Steffen Trumtrar <>,
	Peter Crosthwaite <>,
	"open list:GPIO SUBSYSTEM" <>,
	Rob Herring <>,
	Linux ARM <>
Subject: Re: [PATCH] gpio: zynq: Setup chip->base based on alias ID
Date: Wed, 2 May 2018 12:10:32 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Thu, Apr 26, 2018 at 3:35 PM, Michal Simek <> wrote:

>> The only use case which I can think about is userspace sysfs
>> and then I would really like to know why these userspace
>> users cannot use the character device that is nowadays
>> supported by libgpiod and there is even patches for some
>> IoT libraries to use it. The character device makes the
>> GPIO Linux "base" irrelevant for userspace.
>> GPIO sysfs is deprecated and moved to the obsolete ABI.
>> If there are legacy applications that use this I would have
>> to consider it, but since this has been -1 since the driver
>> was merged I find that unlikely.
> Yes, it is about legacy application which I have seen recently and there
> is no source code for application calls it because board vendor doesn't
> provide it.
> You are right that -1 was used from the beginning in mainline but
> unfortunately this driver was in vendor tree for a while and it uses 0
> there.
> In upstreaming this was changed to -1 but customers have a lot of code
> which developed against vendor tree and they want to use
> latest&greatest. And without this they are not able to run that
> applications.
> I found that this logic is already in 5 drivers in mainline that's why I
> send this patch to be +1.

I see.

Sadly comaptibility with out-of-tree driver code is none of our
(community) business.

We do pay a lot of effort not to break the ABI to userspace, but
it needs to be an ABI coming from the mainline kernel, not from
a vendor tree.

So to the mainline kernel this is no regression.

Linus Walleij

  reply	other threads:[~2018-05-02 10:10 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-11 13:55 Michal Simek
2018-04-26 13:08 ` Linus Walleij
2018-04-26 13:35   ` Michal Simek
2018-05-02 10:10     ` Linus Walleij [this message]
2018-05-02 10:15       ` Michal Simek
2018-05-02 13:01         ` Linus Walleij
2018-05-02 13:41           ` Michal Simek
2018-05-02 13:56             ` Linus Walleij
2018-05-02 14:19               ` Michal Simek
2018-05-15 13:26                 ` Michal Simek
2018-05-23  9:44                   ` Linus Walleij
2018-05-23 10:26                     ` Michal Simek
2018-05-23  9:42                 ` Linus Walleij
2018-05-23 10:17                   ` Michal Simek

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