From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751646AbaJAOFk (ORCPT ); Wed, 1 Oct 2014 10:05:40 -0400 Received: from mga02.intel.com ([134.134.136.20]:19589 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751283AbaJAOFi (ORCPT ); Wed, 1 Oct 2014 10:05:38 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.04,632,1406617200"; d="scan'208";a="481262173" Date: Wed, 1 Oct 2014 17:04:41 +0300 From: Mika Westerberg To: Arnd Bergmann Cc: "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, devicetree@vger.kernel.org, Greg Kroah-Hartman , Linus Walleij , Alexandre Courbot , Dmitry Torokhov , Bryan Wu , Lee Jones , Grant Likely , Aaron Lu , Darren Hart Subject: Re: [PATCH v3 10/15] leds: leds-gpio: Add ACPI probing support Message-ID: <20141001140441.GF1786@lahna.fi.intel.com> References: <1410868367-11056-1-git-send-email-mika.westerberg@linux.intel.com> <5364565.aEcZqpzdLW@wuerfel> <20141001115901.GD1786@lahna.fi.intel.com> <2043842.LxdgdYRbIF@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2043842.LxdgdYRbIF@wuerfel> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 01, 2014 at 03:52:42PM +0200, Arnd Bergmann wrote: > On Wednesday 01 October 2014 14:59:01 Mika Westerberg wrote: > > On Wed, Oct 01, 2014 at 12:01:34PM +0200, Arnd Bergmann wrote: > > > On Wednesday 01 October 2014 12:13:09 Mika Westerberg wrote: > > > > > > > > > Regarding the MODULE_DEVICE_TABLE, I suspect the above won't work the > > > > > way you are hoping for, because once you get to dozens or hundreds of > > > > > drivers doing this, each device will show up with the same string, > > > > > so udev will try to load all the modules that list "PRP0001". That > > > > > doesn't look right. With the code from patch 3, you can probably drop > > > > > the acpi MODULE_DEVICE_TABLE() entirely and get the correct behavior. > > > > > > > > It actually works like this now: > > > > > > > > # cd /sys/bus/platform/devices/PRP0001\:00/ > > > > DRIVER=leds-gpio > > > > MODALIAS=of:Nprp0001TacpiCgpio-leds > > > > > > > > # cat modalias > > > > of:Nprp0001TacpiCgpio-leds > > > > > > > > In other words the modalias changes to be of:Nprp0001Tacpi, e.g > > > > name=prp0001, type=acpi and then list of compatible values. > > > > > > > > Udev then loads only module that matches the modalias so it should not > > > > load everything listing PRP0001 in their MODULE_DEVICE_TABLE(). > > > > > > I'm not completely following yet. I can see how this works now, but > > > how is this better than just using the existing modalias for OF? > > > > You mean using just what of_device_get_modalias() would create? In that > > case, what do we put to name and type fields? > > Sorry, I think we're still both misunderstanding one another. You were > talking about the modalias created by the device scanning above, while > I meant the one in the MODULE_DEVICE_TABLE. Right, got it now. > With the entry you create in create_modalias(), you will only ever > match against the MODULE_DEVICE_TABLE(of, of_gpio_leds_match) > line, not against the MODULE_DEVICE_TABLE(acpi, acpi_gpio_leds_match), > so I think you can just drop the latter. Indeed. > On the question what to put into the name and type fields, that is > unrelated. The type is supposed to be for the 'device_type' property > in DT, which we should never rely on in a driver that supports both > APCI and DT. In Linux we only use that for "pci", "cpu" and "memory", > all of which have their own way of getting probed in ACPI. > The "name" is normally ignored in DT as well, except for backwards > compatibility with old bindings, but I would argue that you should not > just put "prp0001" in there. Either leave it empty like type, or use > the name of the device as it appears in the ACPI tables, such as "DEV0" > or "PWM". OK, I think it makes sense to leave them empty. I remember I tried that at some point but it didn't work without N and T fields. Is there some example what to put there in case of empty? Something like "of:N*T*Cgpio-leds" perhaps?