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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48F4CECAAD8 for ; Wed, 21 Sep 2022 19:52:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229745AbiIUTv7 (ORCPT ); Wed, 21 Sep 2022 15:51:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229473AbiIUTv5 (ORCPT ); Wed, 21 Sep 2022 15:51:57 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0B8C58E988; Wed, 21 Sep 2022 12:51:57 -0700 (PDT) Received: from zn.tnic (p200300ea9733e77f329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ea:9733:e77f:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 6D68D1EC058B; Wed, 21 Sep 2022 21:51:51 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1663789911; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=8DJCtm+AGQW+D9iEfDkNEgfP/xvG+kPWvU5Z7Kgh+Pg=; b=Zn2ZhEzdpvYtf90dGnrIHXcsjl0swnVCCbqksE8wDq6uZ6VCOOHXGS8io3JvD50Oo3t14b GpmL/JJFiGwIVB2K0s54P7sfjRp+uE7AsNdJT0UTU7Wnt7TR86cO345jLw0lTwEawVT6KX aPvplQTwkYIbg6i3gvCFzjZ5AoFJY78= Date: Wed, 21 Sep 2022 21:51:51 +0200 From: Borislav Petkov To: Dave Hansen Cc: K Prateek Nayak , linux-kernel@vger.kernel.org, rafael@kernel.org, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, dave.hansen@linux.intel.com, tglx@linutronix.de, andi@lisas.de, puwen@hygon.cn, mario.limonciello@amd.com, peterz@infradead.org, rui.zhang@intel.com, gpiccoli@igalia.com, daniel.lezcano@linaro.org, ananth.narayan@amd.com, gautham.shenoy@amd.com, Calvin Ong , stable@vger.kernel.org, regressions@lists.linux.dev Subject: Re: [PATCH] ACPI: processor_idle: Skip dummy wait for processors based on the Zen microarchitecture Message-ID: References: <20220921063638.2489-1-kprateek.nayak@amd.com> <2b6143b6-9db4-05bc-1e8d-c5d129126f99@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <2b6143b6-9db4-05bc-1e8d-c5d129126f99@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Wed, Sep 21, 2022 at 07:15:07AM -0700, Dave Hansen wrote: > In the end, the delay is because of buggy, circa 2006 chipsets? So, we > use a CPU vendor specific check to approximate that the chipset is > recent and not affected by the bug? If so, is there no better way to > check for a newer chipset than this? So I did some git archeology but that particular addition is in some conglomerate, glued-together patch from 2007 which added the cpuidle tree: commit 4f86d3a8e297205780cca027e974fd5f81064780 Author: Len Brown Date: Wed Oct 3 18:58:00 2007 -0400 cpuidle: consolidate 2.6.22 cpuidle branch into one patch so the most precise check here should be to limit that dummy read to that Intel chipset which needed it. Damned if I knew how to figure out which... -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette