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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0CD9DC433EF for ; Tue, 4 Jan 2022 15:55:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235336AbiADPzW (ORCPT ); Tue, 4 Jan 2022 10:55:22 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:33370 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232465AbiADPzL (ORCPT ); Tue, 4 Jan 2022 10:55:11 -0500 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: kholk11) with ESMTPSA id 0AD2E1F43593 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1641311709; bh=3smna2rui85hd0ub3WLoyVobn8DHHP5eQqp8Q9TuRHo=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=fqocVfDSEzNSK52a1s2yP91kT0QXrE28aLrYgLgVVnizYZzYBoHRC2lC+TVQDCOIe Kz/qm0Giepgg9FQ/4K4GvgpSGVaLLfvKI5HIzdcKxPm3F55DCVGI9LMwRTNfZd8UK+ NvEMzUrqVmUOQq/DAbZWexY6h8ORgfusoKnRryDXpwAbyPmx9eRnZrTFORJNXtWkWY K+XxN6vU06x1aNKWnUfWN89rFgo1OHflAJW+9/wEVjJMzmYCvMepROSGRUKb2PpMkF QJfGCz3JyVqNMEiGDtSb+/rFXoMK2sD+jhT5m+lrC3iHDjA7319nckiAz8zh7T0wKR TM5MCOR2+FQBw== 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 References: <20210923115840.17813-1-yong.wu@mediatek.com> <20210923115840.17813-14-yong.wu@mediatek.com> From: AngeloGioacchino Del Regno Message-ID: <1cb7458d-a012-2e84-82bd-7e4f30ed9162@collabora.com> Date: Tue, 4 Jan 2022 16:55:06 +0100 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=iso-8859-15; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Il 23/09/21 13:58, Yong Wu ha scritto: > 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 > 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. Do you mean that the register write seemingly succeeds but the hardware discards it? Please, reword the `a` sentence to be clearer. > 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. Please reword this comment to explain the entire situation. > + */ > 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 >