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 7A831C433EF for ; Fri, 22 Oct 2021 14:03:29 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 2409F60FC3 for ; Fri, 22 Oct 2021 14:03:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2409F60FC3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id DB7946085E; Fri, 22 Oct 2021 14:03:28 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id BR5fpII4M1dW; Fri, 22 Oct 2021 14:03:28 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp3.osuosl.org (Postfix) with ESMTPS id 976CB60858; Fri, 22 Oct 2021 14:03:27 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 60689C001F; Fri, 22 Oct 2021 14:03:27 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 60E9CC001E for ; Fri, 22 Oct 2021 14:03:25 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 38E4240153 for ; Fri, 22 Oct 2021 14:03:25 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id iqM0JrWOCIPq for ; Fri, 22 Oct 2021 14:03:24 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [46.235.227.227]) by smtp2.osuosl.org (Postfix) with ESMTPS id 1E3EC400C3 for ; Fri, 22 Oct 2021 14:03:24 +0000 (UTC) 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 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-Language: en-US Cc: youlin.pei@mediatek.com, devicetree@vger.kernel.org, Collabora Kernel ML , srv_heupstream@mediatek.com, Krzysztof Kozlowski , linux-kernel@vger.kernel.org, yen-chang.chen@mediatek.com, chao.hao@mediatek.com, iommu@lists.linux-foundation.org, linux-mediatek@lists.infradead.org, Hsin-Yi Wang , anan.sun@mediatek.com, linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 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" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" 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 > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu