From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: [PATCH 0/2] i2c-dev: Don't let userspace block adapter Date: Wed, 6 Jul 2016 08:34:49 -0700 Message-ID: <20160706153449.GL2671@ubuntu> References: <577D1895.3060202@metafoo.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <577D1895.3060202@metafoo.de> Sender: linux-kernel-owner@vger.kernel.org To: Lars-Peter Clausen Cc: Wolfram Sang , Jean Delvare , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, Johan Hovold , Alex Elder List-Id: linux-i2c@vger.kernel.org On 06-07-16, 16:41, Lars-Peter Clausen wrote: > On 07/06/2016 04:57 AM, Viresh Kumar wrote: > > Hi Wolfram/Jean, > > > > I am part of the kernel team for Google's projectara [1], where we are > > building a module smart phone. > > > > This series tries to fix one of the problems we hit on our system as we > > are required to hotplug pretty much every thing on the phone and so this > > fixes hotplug issues with i2c-dev. > > > > As described in the second patch, the current implementation of i2c-dev > > file operations doesn't let the modules (hardware attached to the phone) > > eject from the phone as the cleanup path for the module hasn't finished > > yet (i2c adapter not removed). > > > > We can't let the userspace block the kernel devices forever in such > > cases. > > > > I was able to test them on the ARA phone with kernel 3.10 only and not > > mainline. > > This sounds like you want hot-unplug. This is currently not support by the > I2C framework for adapters. A better approach compared to this series might > be to implement full hot-unplug support for I2C adapters. This will probably > also be useful for additional usecases. Yeah, we need hot-unplug. Hmm, doing that would require more knowledge of the framework and I am afraid I don't have it right now, not that it can't be done :) -- viresh