From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 557AF15C9 for ; Wed, 26 Jul 2023 03:06:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 096C8C433C8; Wed, 26 Jul 2023 03:06:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690340767; bh=NEOYLP0iznHbMTzUU1WZ7txltHSA0/SCINhS/IbFbPU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=KKKZzkFQ3GhIJTIU/R3X+a3LwSNBQmigXdNNLlKxV3HynLFUp12f+shUAsV7nxE2T apogwZkAs2KQ7wfnRbRWr95TdgVmepWi1R23/+XyUiIQApr01h3GCVXlM1x0mle4wU WC7tz3XK5lZzP6O+MgSwphNVisONDwNgpT8o4E3c/zvDlFie7x7rBfjQAr/dzM8QC3 7Kz85d6c0k9fSbOT7eGKSYnfpBtkIJGLGQSbMEi/gF+W5URn93dyKZWXACYKSl88jZ gpYYGeENSvyhTtEjLdl7Qmd7I7dpB44Wh3pYaT1tvdFCwWmIcDeS2MsWL1o/OkGC7J XOTvSM0taNrOw== Date: Tue, 25 Jul 2023 20:06:06 -0700 From: Jakub Kicinski To: Richard Cochran Cc: Johannes Zink , Giuseppe Cavallaro , Alexandre Torgue , Jose Abreu , "David S. Miller" , Eric Dumazet , Paolo Abeni , Maxime Coquelin , Russell King , patchwork-jzi@pengutronix.de, netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel@pengutronix.de, kernel test robot Subject: Re: [PATCH v2] net: stmmac: correct MAC propagation delay Message-ID: <20230725200606.5264b59c@kernel.org> In-Reply-To: <20230719-stmmac_correct_mac_delay-v2-1-3366f38ee9a6@pengutronix.de> References: <20230719-stmmac_correct_mac_delay-v2-1-3366f38ee9a6@pengutronix.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 24 Jul 2023 12:01:31 +0200 Johannes Zink wrote: > The IEEE1588 Standard specifies that the timestamps of Packets must be > captured when the PTP message timestamp point (leading edge of first > octet after the start of frame delimiter) crosses the boundary between > the node and the network. As the MAC latches the timestamp at an > internal point, the captured timestamp must be corrected for the > additional path latency, as described in the publicly available > datasheet [1]. > > This patch only corrects for the MAC-Internal delay, which can be read > out from the MAC_Ingress_Timestamp_Latency register, since the Phy > framework currently does not support querying the Phy ingress and egress > latency. The Closs Domain Crossing Circuits errors as indicated in [1] > are already being accounted in the stmmac_get_tx_hwtstamp() function and > are not corrected here. > > As the Latency varies for different link speeds and MII > modes of operation, the correction value needs to be updated on each > link state change. > > As the delay also causes a phase shift in the timestamp counter compared > to the rest of the network, this correction will also reduce phase error > when generating PPS outputs from the timestamp counter. > > [1] i.MX8MP Reference Manual, rev.1 Section 11.7.2.5.3 "Timestamp > correction" Hi Richard, any opinion on this one? The subject read to me like it's about *MII clocking delays, I figured you may have missed it, too. > diff --git a/drivers/net/ethernet/stmicro/stmmac/hwif.h b/drivers/net/ethernet/stmicro/stmmac/hwif.h > index 6ee7cf07cfd7..95a4d6099577 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/hwif.h > +++ b/drivers/net/ethernet/stmicro/stmmac/hwif.h > @@ -536,6 +536,7 @@ struct stmmac_hwtimestamp { > void (*get_systime) (void __iomem *ioaddr, u64 *systime); > void (*get_ptptime)(void __iomem *ioaddr, u64 *ptp_time); > void (*timestamp_interrupt)(struct stmmac_priv *priv); > + void (*correct_latency)(struct stmmac_priv *priv); > }; > > #define stmmac_config_hw_tstamping(__priv, __args...) \ > @@ -554,6 +555,8 @@ struct stmmac_hwtimestamp { > stmmac_do_void_callback(__priv, ptp, get_ptptime, __args) > #define stmmac_timestamp_interrupt(__priv, __args...) \ > stmmac_do_void_callback(__priv, ptp, timestamp_interrupt, __args) > +#define stmmac_correct_latency(__priv, __args...) \ > + stmmac_do_void_callback(__priv, ptp, correct_latency, __args) > > struct stmmac_tx_queue; > struct stmmac_rx_queue; > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c > index fa2c3ba7e9fe..7e0fa024e0ad 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c > @@ -60,6 +60,48 @@ static void config_sub_second_increment(void __iomem *ioaddr, > *ssinc = data; > } > > +static void correct_latency(struct stmmac_priv *priv) > +{ > + void __iomem *ioaddr = priv->ptpaddr; > + u32 reg_tsic, reg_tsicsns; > + u32 reg_tsec, reg_tsecsns; > + u64 scaled_ns; > + u32 val; > + > + /* MAC-internal ingress latency */ > + scaled_ns = readl(ioaddr + PTP_TS_INGR_LAT); > + > + /* See section 11.7.2.5.3.1 "Ingress Correction" on page 4001 of > + * i.MX8MP Applications Processor Reference Manual Rev. 1, 06/2021 > + */ > + val = readl(ioaddr + PTP_TCR); > + if (val & PTP_TCR_TSCTRLSSR) > + /* nanoseconds field is in decimal format with granularity of 1ns/bit */ > + scaled_ns = ((u64)NSEC_PER_SEC << 16) - scaled_ns; > + else > + /* nanoseconds field is in binary format with granularity of ~0.466ns/bit */ > + scaled_ns = ((1ULL << 31) << 16) - > + DIV_U64_ROUND_CLOSEST(scaled_ns * PSEC_PER_NSEC, 466U); > + > + reg_tsic = scaled_ns >> 16; > + reg_tsicsns = scaled_ns & 0xff00; > + > + /* set bit 31 for 2's compliment */ > + reg_tsic |= BIT(31); > + > + writel(reg_tsic, ioaddr + PTP_TS_INGR_CORR_NS); > + writel(reg_tsicsns, ioaddr + PTP_TS_INGR_CORR_SNS); > + > + /* MAC-internal egress latency */ > + scaled_ns = readl(ioaddr + PTP_TS_EGR_LAT); > + > + reg_tsec = scaled_ns >> 16; > + reg_tsecsns = scaled_ns & 0xff00; > + > + writel(reg_tsec, ioaddr + PTP_TS_EGR_CORR_NS); > + writel(reg_tsecsns, ioaddr + PTP_TS_EGR_CORR_SNS); > +} > + > static int init_systime(void __iomem *ioaddr, u32 sec, u32 nsec) > { > u32 value; > @@ -221,4 +263,5 @@ const struct stmmac_hwtimestamp stmmac_ptp = { > .get_systime = get_systime, > .get_ptptime = get_ptptime, > .timestamp_interrupt = timestamp_interrupt, > + .correct_latency = correct_latency, > }; > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > index efe85b086abe..ee78e69e9ae3 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > @@ -909,6 +909,8 @@ static int stmmac_init_ptp(struct stmmac_priv *priv) > priv->hwts_tx_en = 0; > priv->hwts_rx_en = 0; > > + stmmac_correct_latency(priv, priv); > + > return 0; > } > > @@ -1094,6 +1096,8 @@ static void stmmac_mac_link_up(struct phylink_config *config, > > if (priv->dma_cap.fpesel) > stmmac_fpe_link_state_handle(priv, true); > + > + stmmac_correct_latency(priv, priv); > } > > static const struct phylink_mac_ops stmmac_phylink_mac_ops = { > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h > index bf619295d079..d1fe4b46f162 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h > @@ -26,6 +26,12 @@ > #define PTP_ACR 0x40 /* Auxiliary Control Reg */ > #define PTP_ATNR 0x48 /* Auxiliary Timestamp - Nanoseconds Reg */ > #define PTP_ATSR 0x4c /* Auxiliary Timestamp - Seconds Reg */ > +#define PTP_TS_INGR_CORR_NS 0x58 /* Ingress timestamp correction nanoseconds */ > +#define PTP_TS_EGR_CORR_NS 0x5C /* Egress timestamp correction nanoseconds*/ > +#define PTP_TS_INGR_CORR_SNS 0x60 /* Ingress timestamp correction subnanoseconds */ > +#define PTP_TS_EGR_CORR_SNS 0x64 /* Egress timestamp correction subnanoseconds */ > +#define PTP_TS_INGR_LAT 0x68 /* MAC internal Ingress Latency */ > +#define PTP_TS_EGR_LAT 0x6c /* MAC internal Egress Latency */ > > #define PTP_STNSUR_ADDSUB_SHIFT 31 > #define PTP_DIGITAL_ROLLOVER_MODE 0x3B9ACA00 /* 10e9-1 ns */ > > --- > base-commit: ba80e20d7f3f87dab3f9f0c0ca66e4b1fcc7be9f > change-id: 20230719-stmmac_correct_mac_delay-4278cb9d9bc1 > > Best regards,