From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Subject: Re: [PATCH v1] iommu/ipmmu-vmsa: Don't register as BUS IOMMU if machine doesn't have IPMMU-VMSA Date: Fri, 27 Jul 2018 12:10:15 +0300 Message-ID: <2725801.tsBI9ZhLPt@avalon> References: <20180726211916.10264-1-digetx@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: <20180726211916.10264-1-digetx@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Dmitry Osipenko Cc: Joerg Roedel , Laurent Pinchart , Marc Dietrich , iommu@lists.linux-foundation.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven , Magnus Damm List-Id: iommu@lists.linux-foundation.org Hi Dmitry, (CC'ing Geert and Magnus) Thank you for the patch. On Friday, 27 July 2018 00:19:16 EEST Dmitry Osipenko wrote: > This fixes kernel crashing on NVIDIA Tegra if kernel is compiled in > a multiplatform configuration and IPMMU-VMSA driver is enabled. > > Cc: # v3.20+ > Signed-off-by: Dmitry Osipenko > --- > drivers/iommu/ipmmu-vmsa.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c > index 9e8495762bc8..78c50db9cd71 100644 > --- a/drivers/iommu/ipmmu-vmsa.c > +++ b/drivers/iommu/ipmmu-vmsa.c > @@ -1109,12 +1109,19 @@ static struct platform_driver ipmmu_driver = { > > static int __init ipmmu_init(void) > { > + struct device_node *np; > static bool setup_done; > int ret; > > if (setup_done) > return 0; > > + np = of_find_matching_node(NULL, ipmmu_of_ids); > + if (!np) > + return 0; > + > + of_node_put(np); > + While functionally correct, this will add some unnecessary overhead when iommu_init() is called from IOMMU_OF_DECLARE(). I'm OK with this fix as a temporary measure to solve your problem, but we need to address the underlying issue properly. Geert, Magnus, the ipmmu-vmsa driver is a bit of a mess. We should brush it up and start using IOMMU_OF_DECLARE() on all platforms (and eventually get rid of bus_set_iommu() completely...). Do you have plans to address this ? If not, could you please add it to your to-do list ? > ret = platform_driver_register(&ipmmu_driver); > if (ret < 0) > return ret; -- Regards, Laurent Pinchart