From mboxrd@z Thu Jan 1 00:00:00 1970 From: Prarit Bhargava Subject: Re: [PATCH RFC] i2c algo, Add i2c-algo-i801 driver [v1] Date: Wed, 09 Apr 2014 14:02:18 -0400 Message-ID: <53458B2A.30003@redhat.com> References: <1397060563-30431-1-git-send-email-prarit@redhat.com> <1397061392.5276.11.camel@x230> <53457D0D.7020805@redhat.com> <1397063381.5276.17.camel@x230> <5345849F.6070909@redhat.com> <1397065034.5276.19.camel@x230> <53458992.4060003@redhat.com> <1397066342.5276.21.camel@x230> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1397066342.5276.21.camel@x230> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Matthew Garrett Cc: "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "rjw-LthD3rsA81gm4RdzfppkhA@public.gmane.org" , "seth.heasley-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org" , "khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org" , "janet.morgan-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org" , "bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org" , "mstowe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org" , "linux-acpi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-i2c@vger.kernel.org On 04/09/2014 01:59 PM, Matthew Garrett wrote: > On Wed, 2014-04-09 at 13:55 -0400, Prarit Bhargava wrote: >> >> On 04/09/2014 01:37 PM, Matthew Garrett wrote: >>> Right. It's dangerous, which is why we forbid it by default. How do we >>> benefit from having a driver that's no safer? >> >> We have yet to see where the existing case exhibits the behaviour of a race. In >> fact, AFAICT, all we've seen is stability. So it's no safer? Yep. It's as >> equally not racy as the existing workaround. > > So... why add the driver at all? Refusing to permit the kernel to touch > these resources is a deliberate design choice, because of the potential > for these races. It'll work absolutely fine right up until the point > where you end up reading the wrong temperature value from an i2c hwmon > chip and perform a critical thermal shutdown. Because it seems like the "right" thing to do is use the ACPI interface rather than the i801 pci driver. At least to me that makes sense. OTOH, if Jean thinks there isn't a need I can drop it. P. >