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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9E8E7C433EF for ; Wed, 1 Jun 2022 13:55:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=dUFlokSQEUhx4iKmBCwSCTApGUrAdQh0Cv2J37eDGnk=; b=H98hPS9WTxCc4e Z+OB9qG1CAPS8obU9dyunJt93wSUTB8hp56EXIhgKzqzdJm4joRx3UpRH3w+r0thgjF2lzJJodSUp ZkvUMzddy++XmgWPHXNCN8aZUWErLj5Xho0b0bMZ2mLuL1845hnYrptI99JAEh66mD60Vwkm+IVBT 5akuGGtQ5/eKgN1lf+NAdY1U1NTmERm1S8TfVgCAMj1VJUVz4e2oyevOcue1O7NR9PbxXt5aGKiNT SykpklmW9iSVDKYt85qz5eykdexDU0muw5k6uTcaKETV6tZvPqkMeyqW0GSEIx/B0TGxqoHHTxhvu plPz82CGHNcXJ7CZbMrg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nwOnw-00GP5f-4c; Wed, 01 Jun 2022 13:54:32 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nwOmn-00GOOF-EM; Wed, 01 Jun 2022 13:53:25 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E69F9615C4; Wed, 1 Jun 2022 13:53:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D241C3411F; Wed, 1 Jun 2022 13:53:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654091598; bh=r3DLkc6jEcY3i0/3z56pH0qiShiXBiSeWD+DV9othKc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G297vWd24QTYYN8UVhD/TX1OSFHuraIhEjO6QHdxM23UILW+Dd15Mzk1790p5UJXi d8ljLl4YFLuwPga5T17I5vCi/eCahcgmB7own6W5OWFF3zciw1JIJryzoRMXC/SXKG bekoqvwupBzFHW/fC3UWpqeUv/ADv8LFieZHpXjkCdeaf6DxFqiaW2d9evvf+peUKu 4+b58QZZ9lr4Ajtiz1ZlykBepn/pSHb/Z4Kud3fqGdOw5xf/bVXTKUX9wmxrlSwOpP dXw4j8VwCfUh6DcpWet9zA79DhdTXjscxx8HXaWeN4CGs3jHpo45MwxisQl/+Xn8Bk pB8fynyOebNFg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Viresh Kumar , Rex-BC Chen , Jia-wei Chang , Matthias Brugger , "Rafael J . Wysocki" , Sasha Levin , rafael@kernel.org, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: [PATCH AUTOSEL 5.18 28/49] cpufreq: Avoid unnecessary frequency updates due to mismatch Date: Wed, 1 Jun 2022 09:51:52 -0400 Message-Id: <20220601135214.2002647-28-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220601135214.2002647-1-sashal@kernel.org> References: <20220601135214.2002647-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220601_065321_558514_E361E213 X-CRM114-Status: GOOD ( 15.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Viresh Kumar [ Upstream commit f55ae08c89873e140c7cac2a7fa161d31a0d60cf ] For some platforms, the frequency returned by hardware may be slightly different from what is provided in the frequency table. For example, hardware may return 499 MHz instead of 500 MHz. In such cases it is better to avoid getting into unnecessary frequency updates, as we may end up switching policy->cur between the two and sending unnecessary pre/post update notifications, etc. This patch has chosen allows the hardware frequency and table frequency to deviate by 1 MHz for now, we may want to increase it a bit later on if someone still complains. Reported-by: Rex-BC Chen Signed-off-by: Viresh Kumar Tested-by: Jia-wei Chang Reviewed-by: Matthias Brugger Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- drivers/cpufreq/cpufreq.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 80f535cc8a75..fbaa8e6c7d23 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -28,6 +28,7 @@ #include #include #include +#include #include static LIST_HEAD(cpufreq_policy_list); @@ -1707,6 +1708,16 @@ static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, b return new_freq; if (policy->cur != new_freq) { + /* + * For some platforms, the frequency returned by hardware may be + * slightly different from what is provided in the frequency + * table, for example hardware may return 499 MHz instead of 500 + * MHz. In such cases it is better to avoid getting into + * unnecessary frequency updates. + */ + if (abs(policy->cur - new_freq) < HZ_PER_MHZ) + return policy->cur; + cpufreq_out_of_sync(policy, new_freq); if (update) schedule_work(&policy->update); -- 2.35.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel