From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755325AbaD2M5H (ORCPT ); Tue, 29 Apr 2014 08:57:07 -0400 Received: from mail-ee0-f51.google.com ([74.125.83.51]:39248 "EHLO mail-ee0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750952AbaD2M5E (ORCPT ); Tue, 29 Apr 2014 08:57:04 -0400 From: Grant Likely Subject: Re: [PATCH 01/10] of: Keep track of populated platform devices To: Rob Herring , Pawel Moll Cc: Rob Herring , Samuel Ortiz , Lee Jones , Arnd Bergmann , Greg Kroah-Hartman , Russell King , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "arm@kernel.org" , "devicetree@vger.kernel.org" In-Reply-To: References: <1398707877-22596-1-git-send-email-pawel.moll@arm.com> <1398707877-22596-2-git-send-email-pawel.moll@arm.com> Date: Tue, 29 Apr 2014 13:56:57 +0100 Message-Id: <20140429125657.65910C4089D@trevor.secretlab.ca> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 28 Apr 2014 13:02:28 -0500, Rob Herring wrote: > On Mon, Apr 28, 2014 at 12:57 PM, Pawel Moll wrote: > > In "Device Tree powered" systems, platform devices are usually > > massively populated with of_platform_populate() call, executed > > at some level of initcalls, either by generic architecture > > or by platform-specific code. > > > > There are situations though where certain devices must be > > created (and bound with drivers) before all the others. > > This presents a challenge, as devices created explicitly > > would be created again by of_platform_populate(). > > > > This patch tries to solve that issue in a generic way, > > adding a "populated" flag for a DT node description. > > Once set, this device will never be created again via > > of_* API, so of_platform_populate() will skip such nodes > > (and its children) in a similar way to the non-available > > ones. > > > > Cc: devicetree@vger.kernel.org > > Signed-off-by: Pawel Moll > > --- > > drivers/of/platform.c | 10 ++++++++-- > > include/linux/of.h | 1 + > > 2 files changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/of/platform.c b/drivers/of/platform.c > > index 404d1da..0ae757a 100644 > > --- a/drivers/of/platform.c > > +++ b/drivers/of/platform.c > > @@ -204,7 +204,8 @@ static struct platform_device *of_platform_device_create_pdata( > > { > > struct platform_device *dev; > > > > - if (!of_device_is_available(np)) > > + if (!of_device_is_available(np) || > > + of_node_check_flag(np, OF_POPULATED)) > > This and the amba case should be a test_and_set operation to avoid a > race condition. Yes. It is an unlikely condition at the time that Pawel is handling, but it should also work for later calls to of_platform_populate() which may happen at runtime and in parallel. g.