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 B494EC6FA8E for ; Sun, 26 Feb 2023 14:49:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230006AbjBZOtk (ORCPT ); Sun, 26 Feb 2023 09:49:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229999AbjBZOsU (ORCPT ); Sun, 26 Feb 2023 09:48:20 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 00DC513D7B; Sun, 26 Feb 2023 06:47:45 -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 sin.source.kernel.org (Postfix) with ESMTPS id 1828DCE0E92; Sun, 26 Feb 2023 14:47:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D4F13C4339B; Sun, 26 Feb 2023 14:47:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1677422853; bh=XUK47YBM9rMPfxxEjuBimIL6djaUFTCviZ1xCgBUaP8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nDdkU7ThhP7Uwr+Ehbdzp4VSnUK0S+UmzhKeTrFnPkYS102y46Q7f7RATfNoJoJAw ZWKZlqKiXLdCOkUFWyz02gTLhL7WsUMhZ9kr2PnXIkYEtpidfV88GfrMilbhImH+Pv Ft5i3dxui8CU6EVJMm8btYWvjP3k4wIdvzTXDGxrzPWQ+D9SkXsVCNI4RQCPQDuDgR Iii5Fze8DM0p6FK9b0vBqRqUsm2Xu2g+tXvlQL40kDsl1hWi4IJAaX2F5lGcAEAAxX TNZ0TEANhvZdmXlJEnCpOSTt0nqRl/Fois8NtjZgbvFLDLgzD4N5FwYFnjcyyr8eDH K9dr2DpHU44gg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Siddaraju DH , Gurucharan G , Tony Nguyen , Sasha Levin , jesse.brandeburg@intel.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, richardcochran@gmail.com, intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org Subject: [PATCH AUTOSEL 6.1 17/49] ice: restrict PTP HW clock freq adjustments to 100, 000, 000 PPB Date: Sun, 26 Feb 2023 09:46:17 -0500 Message-Id: <20230226144650.826470-17-sashal@kernel.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230226144650.826470-1-sashal@kernel.org> References: <20230226144650.826470-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netdev@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 53fec5bbe6e00..a3585ede829bb 100644 --- a/drivers/net/ethernet/intel/ice/ice_ptp.c +++ b/drivers/net/ethernet/intel/ice/ice_ptp.c @@ -2293,7 +2293,7 @@ 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; -- 2.39.0