From nobody Mon Sep 15 02:10:53 2025 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 D3046C54EBE for ; Mon, 16 Jan 2023 10:24:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230167AbjAPKYx (ORCPT ); Mon, 16 Jan 2023 05:24:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40652 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229997AbjAPKYr (ORCPT ); Mon, 16 Jan 2023 05:24:47 -0500 Received: from inva021.nxp.com (inva021.nxp.com [92.121.34.21]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8937317CF3; Mon, 16 Jan 2023 02:24:46 -0800 (PST) Received: from inva021.nxp.com (localhost [127.0.0.1]) by inva021.eu-rdc02.nxp.com (Postfix) with ESMTP id 142DB2008E1; Mon, 16 Jan 2023 11:24:45 +0100 (CET) Received: from aprdc01srsp001v.ap-rdc01.nxp.com (aprdc01srsp001v.ap-rdc01.nxp.com [165.114.16.16]) by inva021.eu-rdc02.nxp.com (Postfix) with ESMTP id D16392008DF; Mon, 16 Jan 2023 11:24:44 +0100 (CET) Received: from lsv03267.swis.in-blr01.nxp.com (lsv03267.swis.in-blr01.nxp.com [92.120.147.107]) by aprdc01srsp001v.ap-rdc01.nxp.com (Postfix) with ESMTP id CB780183ABEF; Mon, 16 Jan 2023 18:24:43 +0800 (+08) From: nikhil.gupta@nxp.com To: linux-arm-kernel@lists.infradead.org, Yangbo Lu , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: vakul.garg@nxp.com, rajan.gupta@nxp.com, richardcochran@gmail.com, Nikhil Gupta Subject: [PATCH v1] ptp_qoriq: fix latency in ptp_qoriq_adjtime() operation. Date: Mon, 16 Jan 2023 15:54:40 +0530 Message-Id: <20230116102440.27189-1-nikhil.gupta@nxp.com> X-Mailer: git-send-email 2.17.1 X-Virus-Scanned: ClamAV using ClamSMTP Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Nikhil Gupta 1588 driver loses about 1us in adjtime operation at PTP slave. This is because adjtime operation uses a slow non-atomic tmr_cnt_read() followed by tmr_cnt_write() operation. In the above sequence, since the timer counter operation keeps incrementing, it leads to latency. The tmr_offset register (which is added to TMR_CNT_H/L register gives the current time) must be programmed with the delta nanoseconds. Signed-off-by: Nikhil Gupta Reviewed-by: Yangbo Lu --- drivers/ptp/ptp_qoriq.c | 35 ++++++++++++++++++++++++++++++----- 1 file changed, 30 insertions(+), 5 deletions(-) diff --git a/drivers/ptp/ptp_qoriq.c b/drivers/ptp/ptp_qoriq.c index 08f4cf0ad9e3..69fa77b99b45 100644 --- a/drivers/ptp/ptp_qoriq.c +++ b/drivers/ptp/ptp_qoriq.c @@ -48,6 +48,29 @@ static void tmr_cnt_write(struct ptp_qoriq *ptp_qoriq, u= 64 ns) ptp_qoriq->write(®s->ctrl_regs->tmr_cnt_h, hi); } =20 +static void tmr_offset_write(struct ptp_qoriq *ptp_qoriq, u64 delta_ns) +{ + struct ptp_qoriq_registers *regs =3D &ptp_qoriq->regs; + u32 hi =3D delta_ns >> 32; + u32 lo =3D delta_ns & 0xffffffff; + + ptp_qoriq->write(®s->ctrl_regs->tmroff_l, lo); + ptp_qoriq->write(®s->ctrl_regs->tmroff_h, hi); +} + +static u64 tmr_offset_read(struct ptp_qoriq *ptp_qoriq) +{ + struct ptp_qoriq_registers *regs =3D &ptp_qoriq->regs; + u64 ns; + u32 lo, hi; + + lo =3D ptp_qoriq->read(®s->ctrl_regs->tmroff_l); + hi =3D ptp_qoriq->read(®s->ctrl_regs->tmroff_h); + ns =3D ((u64) hi) << 32; + ns |=3D lo; + return ns; +} + /* Caller must hold ptp_qoriq->lock. */ static void set_alarm(struct ptp_qoriq *ptp_qoriq) { @@ -55,7 +78,9 @@ static void set_alarm(struct ptp_qoriq *ptp_qoriq) u64 ns; u32 lo, hi; =20 - ns =3D tmr_cnt_read(ptp_qoriq) + 1500000000ULL; + ns =3D tmr_cnt_read(ptp_qoriq) + tmr_offset_read(ptp_qoriq) + + 1500000000ULL; + ns =3D div_u64(ns, 1000000000UL) * 1000000000ULL; ns -=3D ptp_qoriq->tclk_period; hi =3D ns >> 32; @@ -212,10 +237,9 @@ int ptp_qoriq_adjtime(struct ptp_clock_info *ptp, s64 = delta) struct ptp_qoriq *ptp_qoriq =3D container_of(ptp, struct ptp_qoriq, caps); =20 spin_lock_irqsave(&ptp_qoriq->lock, flags); - - now =3D tmr_cnt_read(ptp_qoriq); + now =3D tmr_offset_read(ptp_qoriq); now +=3D delta; - tmr_cnt_write(ptp_qoriq, now); + tmr_offset_write(ptp_qoriq, now); set_fipers(ptp_qoriq); =20 spin_unlock_irqrestore(&ptp_qoriq->lock, flags); @@ -232,7 +256,7 @@ int ptp_qoriq_gettime(struct ptp_clock_info *ptp, struc= t timespec64 *ts) =20 spin_lock_irqsave(&ptp_qoriq->lock, flags); =20 - ns =3D tmr_cnt_read(ptp_qoriq); + ns =3D tmr_cnt_read(ptp_qoriq) + tmr_offset_read(ptp_qoriq); =20 spin_unlock_irqrestore(&ptp_qoriq->lock, flags); =20 @@ -253,6 +277,7 @@ int ptp_qoriq_settime(struct ptp_clock_info *ptp, =20 spin_lock_irqsave(&ptp_qoriq->lock, flags); =20 + tmr_offset_write(ptp_qoriq, 0); tmr_cnt_write(ptp_qoriq, ns); set_fipers(ptp_qoriq); =20 --=20 2.17.1