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 D1CEAC433ED for ; Wed, 5 May 2021 15:46:50 +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 354D061155 for ; Wed, 5 May 2021 15:46:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 354D061155 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=whitecape.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8B0746E4B1; Wed, 5 May 2021 15:46:47 +0000 (UTC) X-Greylist: delayed 654 seconds by postgrey-1.36 at gabe; Wed, 05 May 2021 15:46:46 UTC Received: from smtp71.iad3a.emailsrvr.com (smtp71.iad3a.emailsrvr.com [173.203.187.71]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7E92D6E4B1 for ; Wed, 5 May 2021 15:46:45 +0000 (UTC) X-Auth-ID: kenneth@whitecape.org Received: by smtp33.relay.iad3a.emailsrvr.com (Authenticated sender: kenneth-AT-whitecape.org) with ESMTPSA id EBC5C54DF; Wed, 5 May 2021 11:35:50 -0400 (EDT) From: Kenneth Graunke To: Rodrigo Vivi , Joonas Lahtinen , Jani Nikula , Daniel Vetter , =?ISO-8859-1?Q?Andr=E9?= Almeida Subject: Re: Enabling sample_c optimization for Broadwell GPUs Date: Wed, 05 May 2021 08:35:46 -0700 Message-ID: <4570916.7zo566DRWU@mizzik> In-Reply-To: References: MIME-Version: 1.0 X-Classification-ID: 3ad83565-0b7a-44f9-a737-8695edb5ecfb-1-1 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: intel-gfx@lists.freedesktop.org, kernel@collabora.com, dri-devel@lists.freedesktop.org Content-Type: multipart/mixed; boundary="===============1525702179==" Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" --===============1525702179== Content-Type: multipart/signed; boundary="nextPart4240184.CW8T6EejXm"; micalg="pgp-sha256"; protocol="application/pgp-signature" --nextPart4240184.CW8T6EejXm Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1"; protected-headers="v1" From: Kenneth Graunke To: Rodrigo Vivi , Joonas Lahtinen , Jani Nikula , Daniel Vetter , =?ISO-8859-1?Q?Andr=E9?= Almeida Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, kernel@collabora.com Subject: Re: Enabling sample_c optimization for Broadwell GPUs Date: Wed, 05 May 2021 08:35:46 -0700 Message-ID: <4570916.7zo566DRWU@mizzik> In-Reply-To: References: Hello, Yes, that bit only exists on Haswell. On Haswell, sample_c operations were processed at 1 pixel/clock unless you set that bit, in which case they get processed at 4 pixels/clock. The downside is that it breaks some obscure media feature that apparently no one used. Broadwell and later alway process sample_c operations at the fast speed, and there is no bit to control it. I would say that downstream patch is incorrect. =2D-Ken On Tuesday, May 4, 2021 4:07:14 PM PDT Andr=E9 Almeida wrote: > Hi there, >=20 > While browsing an old downstream kernel, I found a patch[0] that enables= =20 > sample_c optimizations at Broadwell GPUs. The message from the upstream=20 > commit that enables it for Haswell[1] (and presumably where the code=20 > at[0] was copied from) states that "[..] later platforms remove this=20 > bit, and apparently always enable the optimization". >=20 > Could you confirm that Broadwell and following architectures enable this= =20 > optimization by default (and thus, patch[0] is a no-op), or should I=20 > upstream it? >=20 > Thanks, > Andr=E9 >=20 > [0]=20 > https://github.com/ValveSoftware/steamos_kernel/commit/198990f13e1d942986= 4c177d9441a6559771c5e2 >=20 > [1]=20 > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit= /?id=3D944115934436b1ff6cf773a9e9123858ea9ef3da >=20 --nextPart4240184.CW8T6EejXm Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. 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