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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 4A4E0C47255 for ; Mon, 11 May 2020 16:17:00 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 201862070B for ; Mon, 11 May 2020 16:16:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 201862070B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9889C6E4F8; Mon, 11 May 2020 16:16:59 +0000 (UTC) Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 57C8D6E4F8 for ; Mon, 11 May 2020 16:16:58 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from localhost (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP (TLS) id 21163092-1500050 for multiple; Mon, 11 May 2020 17:16:53 +0100 MIME-Version: 1.0 In-Reply-To: <158921363228.1729.5879156210323656119@build.alporthouse.com> References: <20200511160803.15407-1-mika.kuoppala@linux.intel.com> <158921363228.1729.5879156210323656119@build.alporthouse.com> From: Chris Wilson To: Mika Kuoppala , intel-gfx@lists.freedesktop.org Message-ID: <158921381209.1729.9885468432351595414@build.alporthouse.com> User-Agent: alot/0.8.1 Date: Mon, 11 May 2020 17:16:52 +0100 Subject: Re: [Intel-gfx] [PATCH] drm/i915: Force pte cacheline to main memory X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Quoting Chris Wilson (2020-05-11 17:13:52) > Quoting Mika Kuoppala (2020-05-11 17:08:03) > > We have problems of tgl not seeing a valid pte entry > > when iommu is enabled. Add heavy handed flushing > > of entry modification by flushing the cpu, cacheline > > and then wcb. This forces the pte out to main memory > > past this point regarless of promises of coherency. > > > > This is an evolution of an experimental patch from > > Chris Wilson of adding wmb for coherent partners, > > by adding a clflush to force the cache->memory step. > > > > Testcase: igt/gem_exec_fence/parallel > > Cc: Chris Wilson > > Signed-off-by: Mika Kuoppala > > Not only does it help tgl, but it is also helping with a coherency > problem on Braswell. We see similar problems on gen9 and icl, and I have > a trybot run to see if it helps with those. It should be noted that Braswell is using WC kmaps of the PTE, so this should not even be necessary... But if we drop the WC and keep the clflush, it fails. Just to add to the confusion. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx