From patchwork Thu Jul 6 16:55:30 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robin Murphy X-Patchwork-Id: 9828671 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id DF72460361 for ; Thu, 6 Jul 2017 16:56:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CEB62286A3 for ; Thu, 6 Jul 2017 16:56:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C3850286E7; Thu, 6 Jul 2017 16:56:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 53F6E286A3 for ; Thu, 6 Jul 2017 16:56:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Owner; bh=l6M+aB+TpOPp1HKLAxVgQekVHdCHqpFV4LBE6nDHgTY=; b=KX5 0VuHwjEP9xK0DvoVi9PbOJahQgXVIGS0atKxEEbpuWt27qEz9uN2wp59a4cgRwXk3b9BpAwUlhnW9 wMINWnNHZHQSWMFtCZHPWoX1bAjezzd9izofNZaKiToe74iCqcXVKVQoyyPxidob66IXiWbT2LxZx X4GNunKqcVR/OhiD9RMLByLq9Ps675RfnbUtOGoP9lkgtP/SvsD21zaoIDRT5MZafGx08kqCypAdd evAFYfLDLmjfDAs3GZgP5yI1cq51uY+7ym/Zt3sgpq5yyG8grLETzvEr+wEgpCLaOstnkz9i5vPsn HbufALGj+z4lJQqX2aIyFW/9C1euwpg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dTA4e-0006Pk-0W; Thu, 06 Jul 2017 16:56:16 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dTA4Q-0006BO-5r; Thu, 06 Jul 2017 16:56:03 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CFE8D344; Thu, 6 Jul 2017 09:55:40 -0700 (PDT) Received: from e110467-lin.cambridge.arm.com (e110467-lin.cambridge.arm.com [10.1.210.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A93203F3E1; Thu, 6 Jul 2017 09:55:39 -0700 (PDT) From: Robin Murphy To: will.deacon@arm.com, joro@8bytes.org Subject: [PATCH 1/2] iommu/mtk: Avoid redundant TLB syncs locally Date: Thu, 6 Jul 2017 17:55:30 +0100 Message-Id: <367e86d1e73867eaf0467732c10c7dc74380f97c.1499360104.git.robin.murphy@arm.com> X-Mailer: git-send-email 2.12.2.dirty X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170706_095602_260961_3E2AD269 X-CRM114-Status: GOOD ( 10.04 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Matthias Brugger , iommu@lists.linux-foundation.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, yong.wu@mediatek.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Under certain circumstances, the io-pgtable code may end up issuing two TLB sync operations without any intervening invalidations. This goes badly for the M4U hardware, since it means the second sync ends up polling for a non-existent operation to finish, and as a result times out and warns. The io_pgtable_tlb_* helpers implement a high-level optimisation to avoid issuing the second sync at all in such cases, but in order to work correctly that requires all pagetable operations to be serialised under a lock, thus is no longer applicable to all io-pgtable users. Since we're the only user actually relying on this flag for correctness, let's reimplement it locally to avoid the headache of trying to make the high-level version concurrency-safe for other users. CC: Yong Wu CC: Matthias Brugger Signed-off-by: Robin Murphy Tested-by: Yong Wu --- drivers/iommu/mtk_iommu.c | 6 ++++++ drivers/iommu/mtk_iommu.h | 1 + 2 files changed, 7 insertions(+) diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c index 5d14cd15198d..91c6d367ab35 100644 --- a/drivers/iommu/mtk_iommu.c +++ b/drivers/iommu/mtk_iommu.c @@ -129,6 +129,7 @@ static void mtk_iommu_tlb_add_flush_nosync(unsigned long iova, size_t size, writel_relaxed(iova, data->base + REG_MMU_INVLD_START_A); writel_relaxed(iova + size - 1, data->base + REG_MMU_INVLD_END_A); writel_relaxed(F_MMU_INV_RANGE, data->base + REG_MMU_INVALIDATE); + data->tlb_flush_active = true; } static void mtk_iommu_tlb_sync(void *cookie) @@ -137,6 +138,10 @@ static void mtk_iommu_tlb_sync(void *cookie) int ret; u32 tmp; + /* Avoid timing out if there's nothing to wait for */ + if (!data->tlb_flush_active) + return; + ret = readl_poll_timeout_atomic(data->base + REG_MMU_CPE_DONE, tmp, tmp != 0, 10, 100000); if (ret) { @@ -146,6 +151,7 @@ static void mtk_iommu_tlb_sync(void *cookie) } /* Clear the CPE status */ writel_relaxed(0, data->base + REG_MMU_CPE_DONE); + data->tlb_flush_active = false; } static const struct iommu_gather_ops mtk_iommu_gather_ops = { diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h index 2a28eadeea0e..c06cc91b5d9a 100644 --- a/drivers/iommu/mtk_iommu.h +++ b/drivers/iommu/mtk_iommu.h @@ -47,6 +47,7 @@ struct mtk_iommu_data { struct iommu_group *m4u_group; struct mtk_smi_iommu smi_imu; /* SMI larb iommu info */ bool enable_4GB; + bool tlb_flush_active; struct iommu_device iommu; };