Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751841AbdISJp0 (ORCPT ); Tue, 19 Sep 2017 05:45:26 -0400 Received: from foss.arm.com ([217.140.101.70]:47792 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751416AbdISJpX (ORCPT ); Tue, 19 Sep 2017 05:45:23 -0400 Date: Tue, 19 Sep 2017 10:45:39 +0100 From: Liviu Dudau To: Laurent Pinchart Cc: Laurent Pinchart , Magnus Damm , Geert Uytterhoeven , Shawn Lin , Joerg Roedel , IOMMU ML , LKML Subject: Re: [PATCH] iommu/ipmmu-vmsa: Do not replace bus IOMMU ops on driver init. Message-ID: <20170919094539.GA10045@e110455-lin.cambridge.arm.com> References: <20170918100444.21878-1-Liviu.Dudau@arm.com> <2550948.Yqn2DEl6fn@avalon> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2550948.Yqn2DEl6fn@avalon> User-Agent: Mutt/1.9.0 (2017-09-02) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3598 Lines: 109 On Tue, Sep 19, 2017 at 10:07:58AM +0300, Laurent Pinchart wrote: > Hi Liviu, > > Thank you for the patch. > > On Monday, 18 September 2017 13:04:44 EEST Liviu Dudau wrote: > > If the IPMMU driver is compiled in the kernel it will replace the > > platform bus IOMMU ops on running the ipmmu_init() function, regardless > > if there is any IPMMU hardware present or not. This screws up systems > > that just want to build a generic kernel that runs on multiple platforms > > and use a different IOMMU implementation. > > > > Move the bus_set_iommu() call at the end of the ipmmu_probe() function > > when we know that hardware is present. With current IOMMU framework it > > should be safe (at least for OF case). > > If I recall correctly the issue is that the IPMMU might be probed after bus > master devices when using the legacy IOMMU DT integration, which the ipmmu- > vmsa driver does on ARM32. Calling bus_set_iommu() from the probe function > will then result in some devices losing IOMMU support. This is on arm64, on the Arm Juno board. > > > Now that the ipmmu_init() and ipmmu_exit() functions are simple calls to > > platform_driver_register() and platform_driver_unregister(), replace > > them with the module_platform_driver() macro call. > > > > Signed-off-by: Liviu Dudau > > Cc: Laurent Pinchart > > --- > > drivers/iommu/ipmmu-vmsa.c | 29 +++++------------------------ > > 1 file changed, 5 insertions(+), 24 deletions(-) > > > > diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c > > index 2a38aa15be17d..c60569c74678d 100644 > > --- a/drivers/iommu/ipmmu-vmsa.c > > +++ b/drivers/iommu/ipmmu-vmsa.c > > @@ -1055,10 +1055,11 @@ static int ipmmu_probe(struct platform_device *pdev) > > ipmmu_device_reset(mmu); > > > > /* > > - * We can't create the ARM mapping here as it requires the bus to have > > - * an IOMMU, which only happens when bus_set_iommu() is called in > > - * ipmmu_init() after the probe function returns. > > + * Now that we have validated the presence of the hardware, set > > + * the bus IOMMU ops to enable future domain and device setup. > > */ > > + if (!iommu_present(&platform_bus_type)) > > + bus_set_iommu(&platform_bus_type, &ipmmu_ops); > > > > spin_lock(&ipmmu_devices_lock); > > list_add(&mmu->list, &ipmmu_devices); > > What branch is this patch based on ? ipmmu_devices_lock isn't in mainline. drm-next. :) Looks like things have move forward since I've made the patch before LPC, will update and resend. Best regards, Liviu > > > @@ -1100,27 +1101,7 @@ static struct platform_driver ipmmu_driver = { > > .remove = ipmmu_remove, > > }; > > > > -static int __init ipmmu_init(void) > > -{ > > - int ret; > > - > > - ret = platform_driver_register(&ipmmu_driver); > > - if (ret < 0) > > - return ret; > > - > > - if (!iommu_present(&platform_bus_type)) > > - bus_set_iommu(&platform_bus_type, &ipmmu_ops); > > - > > - return 0; > > -} > > - > > -static void __exit ipmmu_exit(void) > > -{ > > - return platform_driver_unregister(&ipmmu_driver); > > -} > > - > > -subsys_initcall(ipmmu_init); > > -module_exit(ipmmu_exit); > > +module_platform_driver(ipmmu_driver); > > > > MODULE_DESCRIPTION("IOMMU API for Renesas VMSA-compatible IPMMU"); > > MODULE_AUTHOR("Laurent Pinchart "); > > -- > Regards, > > Laurent Pinchart > -- ==================== | I would like to | | fix the world, | | but they're not | | giving me the | \ source code! / --------------- ¯\_(ツ)_/¯