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,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 4E0C9C433E2 for ; Tue, 1 Sep 2020 17:39:49 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (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 C34972071B for ; Tue, 1 Sep 2020 17:39:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="t4Ef4Ve+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C34972071B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 5640517A9; Tue, 1 Sep 2020 19:38:57 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 5640517A9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1598981987; bh=TEUEbM4vYkBXFl3cUjFLyyUZlmdbqw/yLXBsVNcG3WY=; h=Date:From:To:Subject:References:In-Reply-To:Cc:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=t4Ef4Ve+k1d1jSN5WiU9jYiXFkK+B8vD+cg0yOhD5g6dHzooY9eIloII5FZvCoGwi tG/juR9/6s8+3q7HV+L+iPSm3nKR47cH/6ZVXU/Yahb44cJhmb+L8BoESXGi6dp6vm 5T8mZJlAozKnqyHcMl/nbrhgb+zPp1wLiH0NMoAo= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id DBD6AF8020D; Tue, 1 Sep 2020 19:38:56 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 01D4AF80217; Tue, 1 Sep 2020 19:38:54 +0200 (CEST) Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by alsa1.perex.cz (Postfix) with ESMTP id 86457F800BA for ; Tue, 1 Sep 2020 19:38:48 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 86457F800BA Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1kDAF0-0004vS-00; Tue, 01 Sep 2020 19:38:42 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 46A35C0E70; Tue, 1 Sep 2020 19:38:10 +0200 (CEST) Date: Tue, 1 Sep 2020 19:38:10 +0200 From: Thomas Bogendoerfer To: Christoph Hellwig Subject: Re: [PATCH 22/28] sgiseeq: convert from dma_cache_sync to dma_sync_single_for_device Message-ID: <20200901173810.GA25282@alpha.franken.de> References: <20200819065555.1802761-1-hch@lst.de> <20200819065555.1802761-23-hch@lst.de> <20200901152209.GA14288@alpha.franken.de> <20200901171241.GA20685@alpha.franken.de> <20200901171627.GA8255@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200901171627.GA8255@lst.de> User-Agent: Mutt/1.5.23 (2014-03-12) Cc: alsa-devel@alsa-project.org, linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-nvme@lists.infradead.org, linux-mips@vger.kernel.org, "James E.J. Bottomley" , linux-mm@kvack.org, Marek Szyprowski , linux-samsung-soc@vger.kernel.org, Joonyoung Shim , linux-scsi@vger.kernel.org, iommu@lists.linux-foundation.org, Ben Skeggs , Matt Porter , linux-media@vger.kernel.org, Tom Lendacky , Pawel Osciak , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, linux-parisc@vger.kernel.org, netdev@vger.kernel.org, Seung-Woo Kim , linux-kernel@vger.kernel.org, Kyungmin Park X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Tue, Sep 01, 2020 at 07:16:27PM +0200, Christoph Hellwig wrote: > Well, if IP22 doesn't speculate (which I'm pretty sure is the case), > dma_sync_single_for_cpu should indeeed be a no-op. But then there > also shouldn't be anything in the cache, as the previous > dma_sync_single_for_device should have invalidated it. So it seems like > we are missing one (or more) ownership transfers to the device. I'll > try to look at the the ownership management in a little more detail > tomorrow. this is the problem: /* Always check for received packets. */ sgiseeq_rx(dev, sp, hregs, sregs); so the driver will look at the rx descriptor on every interrupt, so we cache the rx descriptor on the first interrupt and if there was $no rx packet, we will only see it, if cache line gets flushed for some other reason. kick_tx() does a busy loop checking tx descriptors, with just sync_desc_cpu... Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]