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 34546C433EF for ; Mon, 10 Jan 2022 11:40:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244913AbiAJLkj (ORCPT ); Mon, 10 Jan 2022 06:40:39 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:35524 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245005AbiAJLkY (ORCPT ); Mon, 10 Jan 2022 06:40:24 -0500 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: kholk11) with ESMTPSA id 9D1F51F43693 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1641814821; bh=lLxFaS/8aNgFTDG93PFGJERkDDxVogAZUBbb9F4WqdU=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=MQVvmQFhlNkHIT6EFY6BU6mQ7hNNnjke+8GDhqJBH7RTD3jyiy+0Eye6V26RlLgRI 6qxmoy5nClr5TJMh33Bh+GxeFHgwZP+oHf71M/Ysyi4e7dF1jyKaO7VqWcJXPSgdh2 R3LYs7OQ8mq2M7XbmckDX5lovlbVYbNsiIOrRAhc3cpymfxaKrjzC1EMNg0jn2EmeH 5LDGtbgI3CButWUiiR6vt/WOzSySeDzuoH/KGlV4gGooO4tyzOhHGPpoAEo3G+XatM Ef5zn1aUrEpdj/KGid+5n7dOqS5H6l9MzNLFQHTlq2BEB8DX/UI+9MCzxc4A/8BpdM slt+nUAYauYiw== Subject: Re: [PATCH v3 09/33] iommu/mediatek: Remove for_each_m4u in tlb_sync_all To: Yong Wu Cc: Joerg Roedel , Rob Herring , Matthias Brugger , Will Deacon , Robin Murphy , 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, yen-chang.chen@mediatek.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> <83400d36640fc6256972041c882d080ce9aa5fdd.camel@mediatek.com> From: AngeloGioacchino Del Regno Message-ID: <114af71c-58d0-982f-d362-19184a55fb85@collabora.com> Date: Mon, 10 Jan 2022 12:40:18 +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: <83400d36640fc6256972041c882d080ce9aa5fdd.camel@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 Il 10/01/22 11:59, Yong Wu ha scritto: > 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/ > Ok, that's fair. Means that this patch is fine as it is. I'll release by R-b on Dafna's patch, as suggested. Thank you, - Angelo