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 1C55AC433F5 for ; Mon, 10 Jan 2022 10:59:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244343AbiAJK7v (ORCPT ); Mon, 10 Jan 2022 05:59:51 -0500 Received: from mailgw02.mediatek.com ([210.61.82.184]:55386 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S244353AbiAJK7r (ORCPT ); Mon, 10 Jan 2022 05:59:47 -0500 X-UUID: 395cc667b0e14575be2c58eb00d5c3b4-20220110 X-UUID: 395cc667b0e14575be2c58eb00d5c3b4-20220110 Received: from mtkcas10.mediatek.inc [(172.21.101.39)] by mailgw02.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-SHA384 256/256) with ESMTP id 1957887219; Mon, 10 Jan 2022 18:59:44 +0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.792.3; Mon, 10 Jan 2022 18:59:43 +0800 Received: from mhfsdcap04 (10.17.3.154) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Mon, 10 Jan 2022 18:59:42 +0800 Message-ID: <83400d36640fc6256972041c882d080ce9aa5fdd.camel@mediatek.com> Subject: Re: [PATCH v3 09/33] iommu/mediatek: Remove for_each_m4u in tlb_sync_all From: Yong Wu To: AngeloGioacchino Del Regno CC: Joerg Roedel , Rob Herring , "Matthias Brugger" , Will Deacon , Robin Murphy , Krzysztof Kozlowski , Tomasz Figa , , , , , , , Hsin-Yi Wang , , , Date: Mon, 10 Jan 2022 18:59:42 +0800 In-Reply-To: <85987e9a-dfb0-c241-1dde-43c050a78b51@collabora.com> References: <20210923115840.17813-1-yong.wu@mediatek.com> <20210923115840.17813-10-yong.wu@mediatek.com> <22faee018a36a49e4a507b69d087432c8cd689ec.camel@mediatek.com> <85987e9a-dfb0-c241-1dde-43c050a78b51@collabora.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2022-01-10 at 10:16 +0100, AngeloGioacchino Del Regno wrote: > Il 09/01/22 03:48, Yong Wu ha scritto: > > On Tue, 2022-01-04 at 16:55 +0100, AngeloGioacchino Del Regno > > wrote: > > > Il 23/09/21 13:58, Yong Wu ha scritto: > > > > The tlb_sync_all is called from these three functions: > > > > a) flush_iotlb_all: it will be called for each a iommu HW. > > > > b) tlb_flush_range_sync: it already has for_each_m4u. > > > > c) in irq: When IOMMU HW translation fault, Only need flush > > > > itself. > > > > > > > > Thus, No need for_each_m4u in this tlb_sync_all. Remove it. > > > > > > > > Signed-off-by: Yong Wu > > > > --- > > > > drivers/iommu/mtk_iommu.c | 18 +++++++----------- > > > > 1 file changed, 7 insertions(+), 11 deletions(-) > > > > > > > > diff --git a/drivers/iommu/mtk_iommu.c > > > > b/drivers/iommu/mtk_iommu.c > > > > index 6f4f6624e3ac..0b4c30baa864 100644 > > > > --- a/drivers/iommu/mtk_iommu.c > > > > +++ b/drivers/iommu/mtk_iommu.c > > > > @@ -206,19 +206,15 @@ static struct mtk_iommu_domain > > > > *to_mtk_domain(struct iommu_domain *dom) > > > > > > > > static void mtk_iommu_tlb_flush_all(struct mtk_iommu_data > > > > *data) > > > > { > > > > - struct list_head *head = data->hw_list; > > > > - > > > > - for_each_m4u(data, head) { > > > > - if (pm_runtime_get_if_in_use(data->dev) <= 0) > > > > - continue; > > > > + if (pm_runtime_get_if_in_use(data->dev) <= 0) > > > > + return; > > > > > > > > - writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0, > > > > - data->base + data->plat_data- > > > > > inv_sel_reg); > > > > > > > > - writel_relaxed(F_ALL_INVLD, data->base + > > > > REG_MMU_INVALIDATE); > > > > - wmb(); /* Make sure the tlb flush all done */ > > > > + writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0, > > > > + data->base + data->plat_data- > > > > >inv_sel_reg); > > > > + writel_relaxed(F_ALL_INVLD, data->base + > > > > REG_MMU_INVALIDATE); > > > > + wmb(); /* Make sure the tlb flush all done */ > > > > > > There aren't a lot of writes here - not anymore, since you are no > > > longer doing > > > this for_each_m4u()... > > > ...so, please change writel_relaxed() to writel() calls, allowing > > > you > > > to also > > > remove the write barrier at the end (since in the non relaxed > > > version, order is already ensured). > > > > In the "writel", the "__iowmb()" runs before "write_relaxed". Then > > how > > to guarantee the last register was wrote into the HW. Here the > > flush > > all don't have sync(waiting it complete) > > > > That's right, I'm sorry for the invalid proposal. > > Though, there's something else to mention here... if writing > (F_INVLD_EN1 | F_INVLD_EN0) to inv_sel_reg is *required* to happen > before > writing F_ALL_INVLD to REG_MMU_INVALIDATE (which I think is exactly > the > case here), then, in order to ensure write ordering, you should still > use > writel() instead of the relaxed accessor; after which, since (as you > mentioned) > there is no sync readback loop, you can keep that wmb() at the end. The writel_relaxed also makes sure the order. I did try this: https://patchwork.kernel.org/project/linux-mediatek/patch/1570627143-29441-3-git-send-email-yong.wu@mediatek.com/ > > > > > > > > > > > > - pm_runtime_put(data->dev); > > > > - } > > > > + pm_runtime_put(data->dev); > > > > } > > > > > > > > static void mtk_iommu_tlb_flush_range_sync(unsigned long > > > > iova, > > > > size_t size, > > > > > >