From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Westerberg Subject: Re: [PATCH] i2c: Fix modalias for ACPI enumerated I2C devices Date: Sat, 12 Oct 2013 19:18:05 +0300 Message-ID: <20131012161805.GB3521@intel.com> References: <1381414669-26115-1-git-send-email-jarkko.nikula@linux.intel.com> <2393462.4JRAMNeigd@vostro.rjw.lan> <20131012050413.GY3521@intel.com> <2878883.SYGmCkS5Bt@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <2878883.SYGmCkS5Bt-sKB8Sp2ER+y1GS7QM15AGw@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Rafael J. Wysocki" Cc: Jarkko Nikula , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-acpi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Wolfram Sang List-Id: linux-acpi@vger.kernel.org On Sat, Oct 12, 2013 at 03:45:15PM +0200, Rafael J. Wysocki wrote: > On Saturday, October 12, 2013 08:04:13 AM Mika Westerberg wrote: > > On Sat, Oct 12, 2013 at 12:16:02AM +0200, Rafael J. Wysocki wrote: > > > > I think that this is intentional. We don't want that the i2c modalias > > > > matches with the ACPI device (like with the i2c:INTABCD). Instead use ACPI > > > > IDs that are added to the driver to match with the ACPI device. > > > > > > Well, I'm not really sure this was intentional, but I wonder how other bus > > > types work in that respect? > > > > We have the same for platform bus, if that's what you are asking. > > > > It probably doesn't hurt to have this patch applied but it might cause > > inadvertent match if for some reason there is an I2C client driver that > > happens to have INTABCD I2C id in its list. > > Well, if they have that id in their lists, they are supposed to be able to > handle this device, aren't they? What other reason may be there for them > to put that id into their lists? If we have two ACPI enumerated devices, they have following modalias: i2c-device0: i2c:INTABCD:00 acpi:INTABCD i2c-device1: i2c:INTABCD:01 acpi:INTABCD Likelihood that some random I2C driver has INTABCD:00 or INTABCD:01 ids in their list is minimal. However, when you turn it to this: i2c-device0: i2c:INTABCD acpi:INTABCD i2c-device1: i2c:INTABCD acpi:INTABCD It might be possible that we get a match that isn't supposed to happen. Well, OK it is pretty remote but anyway :-)