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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 8F609C433B4 for ; Wed, 5 May 2021 10:17:00 +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 3D0C761157 for ; Wed, 5 May 2021 10:17:00 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3D0C761157 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com 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 2EAB06E043; Wed, 5 May 2021 10:16:59 +0000 (UTC) Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6E56D6E043; Wed, 5 May 2021 10:16:57 +0000 (UTC) IronPort-SDR: Cb5Zi9ecI9IFsEyTsWTxn0481VVP+KM1oGRZCnCFYFz4kAy5GEAT/v1TiY2MYUi5loxp4rzO+O mRc0FOlJiVJA== X-IronPort-AV: E=McAfee;i="6200,9189,9974"; a="262123841" X-IronPort-AV: E=Sophos;i="5.82,274,1613462400"; d="scan'208";a="262123841" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 May 2021 03:16:55 -0700 IronPort-SDR: U30dEnHdvT5+c2dHJR8RccJwK2sbrlrSUFqR2AvVM8RCcQwEarpH+AZ9Bnx8SZFYCG1Cxc0Lyn a5MwFINoEoqw== X-IronPort-AV: E=Sophos;i="5.82,274,1613462400"; d="scan'208";a="458616820" Received: from yueqinya-mobl.amr.corp.intel.com (HELO intel.com) ([10.254.36.228]) by fmsmga003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 May 2021 03:16:54 -0700 Date: Wed, 5 May 2021 06:16:53 -0400 From: Rodrigo Vivi To: =?iso-8859-1?Q?Andr=E9?= Almeida Message-ID: References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Subject: Re: [Intel-gfx] Enabling sample_c optimization for Broadwell GPUs 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: , Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Kenneth Graunke , kernel@collabora.com Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Hi Andre, I'm not familiar with the sample c message optimization. Probably Ken can comment. However I could check the internal spec here and I saw this bit only exists with this meaning in Haswell. For all the other platforms, including Broadwell it got re-purposed with a different meaning and a programming note: "This bit should be programmed to zero (0h) at all times." Also, I could not find any workaround documented anywhere recommending this bit to be set. So, I would not recommend to use it in any product, even downstream. Regardless the state of sample c message optimization in later platforms. Thanks, Rodrigo. On Tue, May 04, 2021 at 08:07:14PM -0300, Andr=E9 Almeida wrote: > Hi there, > = > While browsing an old downstream kernel, I found a patch[0] that enables > sample_c optimizations at Broadwell GPUs. The message from the upstream > commit that enables it for Haswell[1] (and presumably where the code at[0] > was copied from) states that "[..] later platforms remove this bit, and > apparently always enable the optimization". > = > Could you confirm that Broadwell and following architectures enable this > optimization by default (and thus, patch[0] is a no-op), or should I > upstream it? > = > Thanks, > Andr=E9 > = > [0] https://github.com/ValveSoftware/steamos_kernel/commit/198990f13e1d94= 29864c177d9441a6559771c5e2 > = > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/co= mmit/?id=3D944115934436b1ff6cf773a9e9123858ea9ef3da _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx