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 C9116C678D4 for ; Tue, 7 Mar 2023 17:44:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231888AbjCGRoX (ORCPT ); Tue, 7 Mar 2023 12:44:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231912AbjCGRoF (ORCPT ); Tue, 7 Mar 2023 12:44:05 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 679BEA189B for ; Tue, 7 Mar 2023 09:39:54 -0800 (PST) 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 0FB4461520 for ; Tue, 7 Mar 2023 17:39:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2614EC433D2; Tue, 7 Mar 2023 17:39:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678210790; bh=xBDwSXuA3yINWpZ6P1uSHZ99/ZTv5m0eqAsNKnV+XRo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QP4MudxugY11Tu1eGsaD4+cJuhVuKKCwkxMQI2JRAMK2bTytmiAwToA2Yt9lIyX0T 6YrKM9NK/eOQBAKS/Zc6+Y+IO9jQH4uZRGKI+SwV6RDX3hVKijFcXHw0aN1j1xA5E/ Uqdc8sWGugmbzF2fRIAUsy8u7SmBCDQ8UKSR2QYk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Siddaraju DH , Tony Nguyen , Sasha Levin , Gurucharan G Subject: [PATCH 6.2 0653/1001] ice: restrict PTP HW clock freq adjustments to 100, 000, 000 PPB Date: Tue, 7 Mar 2023 17:57:05 +0100 Message-Id: <20230307170049.927022810@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307170022.094103862@linuxfoundation.org> References: <20230307170022.094103862@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Siddaraju DH [ Upstream commit 8aa4318c3a122b8670bc09af142de3872ca63b88 ] The PHY provides only 39b timestamp. With current timing implementation, we discard lower 7b, leaving 32b timestamp. The driver reconstructs the full 64b timestamp by correlating the 32b timestamp with cached_time for performance. The reconstruction algorithm does both forward & backward interpolation. The 32b timeval has overflow duration of 2^32 counts ~= 4.23 second. Due to interpolation in both direction, its now ~= 2.125 second IIRC, going with at least half a duration, the cached_time is updated with periodic thread of 1 second (worst-case) periodicity. But the 1 second periodicity is based on System-timer. With PPB adjustments, if the 1588 timers increments at say double the rate, (2s in-place of 1s), the Nyquist rate/half duration sampling/update of cached_time with 1 second periodic thread will lead to incorrect interpolations. Hence we should restrict the PPB adjustments to at least half duration of cached_time update which translates to 500,000,000 PPB. Since the periodicity of the cached-time system thread can vary, it is good to have some buffer time and considering practicality of PPB adjustments, limiting the max_adj to 100,000,000. Signed-off-by: Siddaraju DH Tested-by: Gurucharan G (A Contingent worker at Intel) Signed-off-by: Tony Nguyen Signed-off-by: Sasha Levin --- drivers/net/ethernet/intel/ice/ice_ptp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c b/drivers/net/ethernet/intel/ice/ice_ptp.c index d63161d73eb16..3abc8db1d0659 100644 --- a/drivers/net/ethernet/intel/ice/ice_ptp.c +++ b/drivers/net/ethernet/intel/ice/ice_ptp.c @@ -2269,7 +2269,7 @@ static void ice_ptp_set_caps(struct ice_pf *pf) snprintf(info->name, sizeof(info->name) - 1, "%s-%s-clk", dev_driver_string(dev), dev_name(dev)); info->owner = THIS_MODULE; - info->max_adj = 999999999; + info->max_adj = 100000000; info->adjtime = ice_ptp_adjtime; info->adjfine = ice_ptp_adjfine; info->gettimex64 = ice_ptp_gettimex64; -- 2.39.2