From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from na01-bl2-obe.outbound.protection.outlook.com (mail-bl2on0145.outbound.protection.outlook.com [65.55.169.145]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 840111A04D8 for ; Thu, 22 Oct 2015 09:52:12 +1100 (AEDT) Message-ID: <1445467912.701.90.camel@freescale.com> Subject: Re: [PATCH v6 22/22] of/platform: Defer probes of registered devices From: Scott Wood To: Rob Herring CC: Tomeu Vizoso , "linux-kernel@vger.kernel.org" , Stephen Warren , Javier Martinez Canillas , Greg Kroah-Hartman , Mark Brown , Thierry Reding , Alan Stern , "Rafael J. Wysocki" , "linux-arm-kernel@lists.infradead.org" , Dmitry Torokhov , "devicetree@vger.kernel.org" , Linus Walleij , "linux-acpi@vger.kernel.org" , Arnd Bergmann , linuxppc-dev , "Hu Mingkai-B21284" Date: Wed, 21 Oct 2015 17:51:52 -0500 In-Reply-To: References: <1442844182-27787-1-git-send-email-tomeu.vizoso@collabora.com> <1442844182-27787-23-git-send-email-tomeu.vizoso@collabora.com> <1445406845.701.55.camel@freescale.com> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2015-10-21 at 08:44 -0500, Rob Herring wrote: > On Wed, Oct 21, 2015 at 12:54 AM, Scott Wood > wrote: > > On Mon, 2015-09-21 at 16:03 +0200, Tomeu Vizoso wrote: > > > Instead of trying to match and probe platform and AMBA devices right > > > after each is registered, delay their probes until device_initcall_sync. > > > > > > This means that devices will start probing once all built-in drivers > > > have registered, and after all platform and AMBA devices from the DT > > > have been registered already. > > > > > > This allows us to prevent deferred probes by probing dependencies on > > > demand. > > > > > > Signed-off-by: Tomeu Vizoso > > > --- > > > > > > Changes in v4: > > > - Also defer probes of AMBA devices registered from the DT as they can > > > also request resources. > > > > > > drivers/of/platform.c | 11 ++++++++--- > > > 1 file changed, 8 insertions(+), 3 deletions(-) > > > > This breaks arch/powerpc/sysdev/fsl_pci.c. The PCI bus is an OF platform > > device, and it must be probed before pcibios_init() which is a > > subsys_initcall(), or else the PCI bus never gets scanned. > > Thanks for the report. This is probably getting dropped, but it could > be disabled for PPC. I don't think that adding another arbitrary arch difference would be the right solution. > Any plans to fix this and make PCI hosts hotplugable? For the scanning > part, generally the host controller drivers are responsible for > scanning their bus now. Scanning from the host controller driver seems like a reasonable goal, though it'd take a bit of digging to extract whatever other things fsl_pci may depend on from the common PPC PCI code, in particular the various things that pcibios_resource_survey() does after all PCI buses have been scanned. There's also check_swiotlb_enabled(), another subsys_initcall, which frees the swiotlb memory if ppc_swiotlb_enable hasn't been set. The PCI host controller probe sets ppc_swiotlb_enable if it wasn't able to create an inbound mapping for all RAM. Even if we were to change that to a later initcall, there's nothing later than late_initcall that we could use. -Scott