From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C60A1C433B4 for ; Thu, 1 Apr 2021 17:12:35 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6818A6139A for ; Thu, 1 Apr 2021 17:12:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6818A6139A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=54ImYBm6H4sKwbvgLTcaUqiJMpLXXy7doveTQbx4Erw=; b=amBQmzri5PYfdBNRH2gHpbbxE JJymIbKe0gVhjn9WCh32dnPF9tWi0pnKv8Fq0EKI3A+JRWRmx0mND5CWOPshhEKorvxGwRN0W8NPM aBihDigUhmZbzeE/IdJtukwDKvIIc17Ewv6dj88rj6FggJz0ewRGCT3Gj2XGK1tOvHog7h6bojEtl 3j9EbCasZqevUe3HCQDyXP0Jxvge46I7KVHHuvO3cnIEGjt5q3+VndaRTmJzvuJiKfOOK5YnUxFYm krxQkE9Shj5Kf+CvM/gb+fifiEdImP+WjNZicWx6wCxINI0swwD1nbIjaUbs2XWeJKOXoWQTLT9np ysdb2CJEw==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lS0qe-00ASUr-Qz; Thu, 01 Apr 2021 17:11:12 +0000 Received: from mail.kernel.org ([198.145.29.99]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lS0qb-00ASTp-C9 for linux-arm-kernel@lists.infradead.org; Thu, 01 Apr 2021 17:11:11 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 39E5161398; Thu, 1 Apr 2021 17:11:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1617297067; bh=PIT2jhNPPa9PR29r77Bt26sck2KltF1OUjlMOqD2BAw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WWQ9pVjULcj6wFn4SulQ8mjPjS0KQqpninOcoNTDiJT/MKxV4sXYbZ/4r4JRZIzVN UY6rpatTGL7J9Yt9aRVsYpXRHrePcl+HFzlbc0sju7FjMsCgPTirCXKqtBzDxwUuHa /ZGL017tvGMyxVh7H0JDMS2WoEbI0X5CNNPzB5YTZu2L5RvuS0qDCxErArsUCojRvZ fdJN5chmZLO+kGt1FAqQdIdqJLWyl5Hq7XorKUw/JZ+tRIDeNh75WhFL3dzV5Y1IgW mZ1x7ByZLf1em040i9Qe9RPG1JUD7jb03Iou8LO0JJAOeL5mByUXGtWFCBJ7rcB5LV Y4CxN2JKHR2Ew== Date: Thu, 1 Apr 2021 18:11:02 +0100 From: Will Deacon To: Jean-Philippe Brucker Cc: joro@8bytes.org, vivek.gautam@arm.com, guohanjun@huawei.com, linux-acpi@vger.kernel.org, zhangfei.gao@linaro.org, lenb@kernel.org, devicetree@vger.kernel.org, kevin.tian@intel.com, robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org, rjw@rjwysocki.net, iommu@lists.linux-foundation.org, sudeep.holla@arm.com, robin.murphy@arm.com, linux-accelerators@lists.ozlabs.org Subject: Re: [PATCH v14 10/10] iommu/arm-smmu-v3: Add stall support for platform devices Message-ID: <20210401171101.GB9447@willie-the-truck> References: <20210401154718.307519-1-jean-philippe@linaro.org> <20210401154718.307519-11-jean-philippe@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210401154718.307519-11-jean-philippe@linaro.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210401_181109_604483_A7A66D8E X-CRM114-Status: GOOD ( 13.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Apr 01, 2021 at 05:47:19PM +0200, Jean-Philippe Brucker wrote: > The SMMU provides a Stall model for handling page faults in platform > devices. It is similar to PCIe PRI, but doesn't require devices to have > their own translation cache. Instead, faulting transactions are parked > and the OS is given a chance to fix the page tables and retry the > transaction. > > Enable stall for devices that support it (opt-in by firmware). When an > event corresponds to a translation error, call the IOMMU fault handler. > If the fault is recoverable, it will call us back to terminate or > continue the stall. Which hardware is this useful for? Stalling adds a fair amount of complexity to the driver, so I don't think we should support it unless we're likely to see platforms that both implement it and do something useful with it. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel