From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yong Wu Subject: Re: [PATCH] iommu/mediatek: Move the tlb_sync into tlb_flush Date: Tue, 8 Oct 2019 16:18:32 +0800 Message-ID: <1570522712.19130.42.camel@mhfsdcap03> References: <1569822142-14303-1-git-send-email-yong.wu@mediatek.com> <20190930120926.t26ydhgggi2scg3e@willie-the-truck> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190930120926.t26ydhgggi2scg3e@willie-the-truck> Sender: linux-kernel-owner@vger.kernel.org To: Will Deacon Cc: Matthias Brugger , Joerg Roedel , Will Deacon , youlin.pei@mediatek.com, anan.sun@mediatek.com, Nicolas Boichat , cui.zhang@mediatek.com, srv_heupstream@mediatek.com, chao.hao@mediatek.com, linux-kernel@vger.kernel.org, Evan Green , Tomasz Figa , iommu@lists.linux-foundation.org, linux-mediatek@lists.infradead.org, Robin Murphy , linux-arm-kernel@lists.infradead.org List-Id: linux-mediatek@lists.infradead.org On Mon, 2019-09-30 at 13:09 +0100, Will Deacon wrote: > On Mon, Sep 30, 2019 at 01:42:22PM +0800, Yong Wu wrote: > > The commit 4d689b619445 ("iommu/io-pgtable-arm-v7s: Convert to IOMMU API > > TLB sync") help move the tlb_sync of unmap from v7s into the iommu > > framework. It helps add a new function "mtk_iommu_iotlb_sync", But it > > lacked the dom->pgtlock, then it will cause the variable > > "tlb_flush_active" may be changed unexpectedly, we could see this warning > > log randomly: > > > > mtk-iommu 10205000.iommu: Partial TLB flush timed out, falling back to > > full flush > > > > To fix this issue, we can add dom->pgtlock in the "mtk_iommu_iotlb_sync". > > And when checking this issue, we find that __arm_v7s_unmap call > > io_pgtable_tlb_add_flush consecutively when it is supersection/largepage, > > this also is potential unsafe for us. There is no tlb flush queue in the > > MediaTek M4U HW. The HW always expect the tlb_flush/tlb_sync one by one. > > If v7s don't always gurarantee the sequence, Thus, In this patch I move > > the tlb_sync into tlb_flush(also rename the function deleting "_nosync"). > > and we don't care if it is leaf, rearrange the callback functions. Also, > > the tlb flush/sync was already finished in v7s, then iotlb_sync and > > iotlb_sync_all is unnecessary. > > > > Besides, there are two minor changes: > > a) Use writel for the register F_MMU_INV_RANGE which is for triggering the > > HW work. We expect all the setting(iova_start/iova_end...) have already > > been finished before F_MMU_INV_RANGE. > > b) Reduce the tlb timeout value from 100000us to 1000us. the original value > > is so long that affect the multimedia performance. > > > > Fixes: 4d689b619445 ("iommu/io-pgtable-arm-v7s: Convert to IOMMU API TLB sync") > > Signed-off-by: Chao Hao > > Signed-off-by: Yong Wu > > --- > > This patch looks break the logic for tlb_flush and tlb_sync. I'm not > > sure if it > > is reasonable. If someone has concern, I could change: > > a) Add dom->pgtlock in the mtk_iommu_iotlb_sync > > b) Add a io_pgtable_tlb_sync in [1]. > > The patch looks ok to me, but please could you split it up so that the > timeout and writel are done separately? Thanks for the quick review, I will separate them. > > Thanks, > > Will