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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11BC8C4332F for ; Fri, 22 Oct 2021 14:03:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0133E60FC3 for ; Fri, 22 Oct 2021 14:03:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233033AbhJVOFo (ORCPT ); Fri, 22 Oct 2021 10:05:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48436 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231905AbhJVOFl (ORCPT ); Fri, 22 Oct 2021 10:05:41 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD307C061764; Fri, 22 Oct 2021 07:03:23 -0700 (PDT) Received: from [IPv6:2a02:810a:880:f54:50fa:5c7d:20f4:e8d3] (unknown [IPv6:2a02:810a:880:f54:50fa:5c7d:20f4:e8d3]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: dafna) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 3DBD31F454AB; Fri, 22 Oct 2021 15:03:21 +0100 (BST) Subject: Re: [PATCH v3 13/33] iommu/mediatek: Remove the power status checking in tlb flush all To: Yong Wu , Joerg Roedel , Rob Herring , Matthias Brugger , Will Deacon , Robin Murphy Cc: Krzysztof Kozlowski , Tomasz Figa , linux-mediatek@lists.infradead.org, srv_heupstream@mediatek.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, Hsin-Yi Wang , youlin.pei@mediatek.com, anan.sun@mediatek.com, chao.hao@mediatek.com, yen-chang.chen@mediatek.com, Collabora Kernel ML References: <20210923115840.17813-1-yong.wu@mediatek.com> <20210923115840.17813-14-yong.wu@mediatek.com> From: Dafna Hirschfeld Message-ID: <6cff0b97-b861-e02d-e76f-2510c962c452@collabora.com> Date: Fri, 22 Oct 2021 16:03:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210923115840.17813-14-yong.wu@mediatek.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi On 23.09.21 13:58, Yong Wu wrote: > To simplify the code, Remove the power status checking in the > tlb_flush_all, remove this: > if (pm_runtime_get_if_in_use(data->dev) <= 0) > continue; > > After this patch, the mtk_iommu_tlb_flush_all will be called from > a) isr > b) pm runtime resume callback > c) tlb flush range fail case > d) iommu_create_device_direct_mappings > -> iommu_flush_iotlb_all > In first three cases, the power and clock always are enabled; d) is direct Regarding case "c) tlb flush range fail case", I found out that this often happens when the iommu is used while it is runtime suspended. For example the mtk-vcodec encoder driver calls "pm_runtime_resume_and_get" only when it starts streaming but buffers allocation is done in 'v4l2_reqbufs' before "pm_runtime_resume_and_get" is called and then I see the warning "Partial TLB flush timed out, falling back to full flush" I am not sure how to fix that issue, but it seems that case 'c)' might indicate that power and clock are actually not enabled. > mapping, the tlb flush is unnecessay since we already have tlb_flush_all > in the pm_runtime_resume callback. When the iommu's power status is > changed to active, the tlb always is clean. > > In addition, there still are 2 reasons that don't add PM status checking > in the tlb flush all: > a) Write tlb flush all register also is ok even though the HW has no > power and clocks. Write ignore. > b) pm_runtime_get_if_in_use(m4udev) is 0 when the tlb_flush_all > is called frm pm_runtime_resume cb. From this point, we can not add > this code above in this tlb_flush_all. > > Signed-off-by: Yong Wu > --- > drivers/iommu/mtk_iommu.c | 20 +++++++------------- > 1 file changed, 7 insertions(+), 13 deletions(-) > > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c > index e9e94944ed91..4a33b6c6b1db 100644 > --- a/drivers/iommu/mtk_iommu.c > +++ b/drivers/iommu/mtk_iommu.c > @@ -204,10 +204,14 @@ static struct mtk_iommu_domain *to_mtk_domain(struct iommu_domain *dom) > return container_of(dom, struct mtk_iommu_domain, domain); > } > > -static void mtk_iommu_tlb_do_flush_all(struct mtk_iommu_data *data) > +static void mtk_iommu_tlb_flush_all(struct mtk_iommu_data *data) > { > unsigned long flags; > > + /* > + * No need get power status since the HW PM status nearly is active > + * when entering here. > + */ > spin_lock_irqsave(&data->tlb_lock, flags); > writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0, > data->base + data->plat_data->inv_sel_reg); > @@ -216,16 +220,6 @@ static void mtk_iommu_tlb_do_flush_all(struct mtk_iommu_data *data) > spin_unlock_irqrestore(&data->tlb_lock, flags); > } > > -static void mtk_iommu_tlb_flush_all(struct mtk_iommu_data *data) > -{ > - if (pm_runtime_get_if_in_use(data->dev) <= 0) > - return; > - > - mtk_iommu_tlb_do_flush_all(data); > - > - pm_runtime_put(data->dev); > -} > - > static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size, > struct mtk_iommu_data *data) > { > @@ -263,7 +257,7 @@ static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size, > if (ret) { > dev_warn(data->dev, > "Partial TLB flush timed out, falling back to full flush\n"); > - mtk_iommu_tlb_do_flush_all(data); > + mtk_iommu_tlb_flush_all(data); > } > > if (has_pm) > @@ -993,7 +987,7 @@ static int __maybe_unused mtk_iommu_runtime_resume(struct device *dev) > * > * Thus, Make sure the tlb always is clean after each PM resume. > */ > - mtk_iommu_tlb_do_flush_all(data); > + mtk_iommu_tlb_flush_all(data); > > /* > * Uppon first resume, only enable the clk and return, since the values of the >