From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Simek Subject: Re: [PATCH] gpio: zynq: Setup chip->base based on alias ID Date: Wed, 2 May 2018 12:15:48 +0200 Message-ID: References: <6ee982f8eb6e07f9ecbb0cc5093152f4a16b9c31.1523454899.git.michal.simek@xilinx.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Linus Walleij , Michal Simek Cc: "linux-kernel@vger.kernel.org" , Michal Simek , Steffen Trumtrar , Peter Crosthwaite , "open list:GPIO SUBSYSTEM" , Rob Herring , Linux ARM List-Id: linux-gpio@vger.kernel.org On 2.5.2018 12:10, Linus Walleij wrote: > 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. I understand your statement. On the other hand it is feature which was permitted in past for some drivers and this is +1. Thanks, Michal From mboxrd@z Thu Jan 1 00:00:00 1970 From: michal.simek@xilinx.com (Michal Simek) Date: Wed, 2 May 2018 12:15:48 +0200 Subject: [PATCH] gpio: zynq: Setup chip->base based on alias ID In-Reply-To: References: <6ee982f8eb6e07f9ecbb0cc5093152f4a16b9c31.1523454899.git.michal.simek@xilinx.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 2.5.2018 12:10, Linus Walleij wrote: > 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. I understand your statement. On the other hand it is feature which was permitted in past for some drivers and this is +1. Thanks, Michal