From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8CAEAC49ED7 for ; Tue, 10 Sep 2019 15:01:50 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5F61E2082C for ; Tue, 10 Sep 2019 15:01:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5F61E2082C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 2AD77DD9; Tue, 10 Sep 2019 15:01:50 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 6385EDC5 for ; Tue, 10 Sep 2019 15:01:49 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp1.linuxfoundation.org (Postfix) with ESMTP id DB8968A2 for ; Tue, 10 Sep 2019 15:01:40 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 65DD228; Tue, 10 Sep 2019 08:01:40 -0700 (PDT) Received: from [10.1.197.57] (e110467-lin.cambridge.arm.com [10.1.197.57]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C724B3F71F; Tue, 10 Sep 2019 08:01:38 -0700 (PDT) Subject: Re: [PATCH] iommu/arm-smmu: fix "hang" when games exit To: Rob Clark , iommu@lists.linux-foundation.org References: <20190907175013.24246-1-robdclark@gmail.com> From: Robin Murphy Message-ID: <418d8426-f299-1269-2b2e-f86677cf22c2@arm.com> Date: Tue, 10 Sep 2019 16:01:37 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190907175013.24246-1-robdclark@gmail.com> Content-Language: en-GB Cc: Rob Clark , Will Deacon , linux-arm-msm@vger.kernel.org, open list , freedreno@lists.freedesktop.org, "moderated list:ARM SMMU DRIVERS" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On 07/09/2019 18:50, Rob Clark wrote: > From: Rob Clark > > When games, browser, or anything using a lot of GPU buffers exits, there > can be many hundreds or thousands of buffers to unmap and free. If the > GPU is otherwise suspended, this can cause arm-smmu to resume/suspend > for each buffer, resulting 5-10 seconds worth of reprogramming the > context bank (arm_smmu_write_context_bank()/arm_smmu_write_s2cr()/etc). > To the user it would appear that the system is locked up. > > A simple solution is to use pm_runtime_put_autosuspend() instead, so we > don't immediately suspend the SMMU device. > > Signed-off-by: Rob Clark > --- > Note: I've tied the autosuspend enable/delay to the consumer device, > based on the reasoning that if the consumer device benefits from using > an autosuspend delay, then it's corresponding SMMU probably does too. > Maybe that is overkill and we should just unconditionally enable > autosuspend. I'm not sure there's really any reason to expect that a supplier's usage model when doing things for itself bears any relation to that of its consumer(s), so I'd certainly lean towards the "unconditional" argument myself. Of course ideally we'd skip resuming altogether in the map/unmap paths (since resume implies a full TLB reset anyway), but IIRC that approach started to get messy in the context of the initial RPM patchset. I'm planning to fiddle around a bit more to clean up the implementation of the new iommu_flush_ops stuff, so I've made a note to myself to revisit RPM to see if there's a sufficiently clean way to do better. In the meantime, though, I don't have any real objection to using some reasonable autosuspend delay on the principle that if we've been woken up to map/unmap one page, there's a high likelihood that more will follow in short order (and in the configuration slow-paths it won't have much impact either way). Robin. > drivers/iommu/arm-smmu.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index c2733b447d9c..73a0dd53c8a3 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -289,7 +289,7 @@ static inline int arm_smmu_rpm_get(struct arm_smmu_device *smmu) > static inline void arm_smmu_rpm_put(struct arm_smmu_device *smmu) > { > if (pm_runtime_enabled(smmu->dev)) > - pm_runtime_put(smmu->dev); > + pm_runtime_put_autosuspend(smmu->dev); > } > > static struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom) > @@ -1445,6 +1445,15 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) > /* Looks ok, so add the device to the domain */ > ret = arm_smmu_domain_add_master(smmu_domain, fwspec); > > +#ifdef CONFIG_PM > + /* TODO maybe device_link_add() should do this for us? */ > + if (dev->power.use_autosuspend) { > + pm_runtime_set_autosuspend_delay(smmu->dev, > + dev->power.autosuspend_delay); > + pm_runtime_use_autosuspend(smmu->dev); > + } > +#endif > + > rpm_put: > arm_smmu_rpm_put(smmu); > return ret; > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu