[PATCH net-next] Revert "net: stmmac: correct MAC propagation delay"

[PATCH net-next] Revert "net: stmmac: correct MAC propagation delay"

[Jakub Kicinski]

This reverts commit 20bf98c94146eb6fe62177817cb32f53e72dd2e8.

Richard raised concerns about correctness of the code on previous
generations of the HW.

Fixes: 20bf98c94146 ("net: stmmac: correct MAC propagation delay")
Link: https://lore.kernel.org/all/ZMGIuKVP7BEotbrn@hoboy.vegasvil.org/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
CC: peppe.cavallaro@st.com
CC: alexandre.torgue@foss.st.com
CC: joabreu@synopsys.com
CC: mcoquelin.stm32@gmail.com
CC: richardcochran@gmail.com
CC: linux@armlinux.org.uk
CC: j.zink@pengutronix.de
---
 drivers/net/ethernet/stmicro/stmmac/hwif.h    |  3 --
 .../ethernet/stmicro/stmmac/stmmac_hwtstamp.c | 43 -------------------
 .../net/ethernet/stmicro/stmmac/stmmac_main.c |  4 --
 .../net/ethernet/stmicro/stmmac/stmmac_ptp.h  |  6 ---
 4 files changed, 56 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/hwif.h b/drivers/net/ethernet/stmicro/stmmac/hwif.h
index 40147ef24963..652af8f6e75f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/hwif.h
+++ b/drivers/net/ethernet/stmicro/stmmac/hwif.h
@@ -532,7 +532,6 @@ 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...) \
@@ -551,8 +550,6 @@ 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 7e0fa024e0ad..fa2c3ba7e9fe 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_hwtstamp.c
@@ -60,48 +60,6 @@ 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;
@@ -263,5 +221,4 @@ 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 19e46e8f626a..e1f1c034d325 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -909,8 +909,6 @@ 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;
 }
 
@@ -1096,8 +1094,6 @@ 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 d1fe4b46f162..bf619295d079 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_ptp.h
@@ -26,12 +26,6 @@
 #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 */
-- 
2.41.0

Re: [PATCH net-next] Revert "net: stmmac: correct MAC propagation delay"

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 26 Jul 2023 15:40:54 -0700 you wrote:
> This reverts commit 20bf98c94146eb6fe62177817cb32f53e72dd2e8.
> 
> Richard raised concerns about correctness of the code on previous
> generations of the HW.
> 
> Fixes: 20bf98c94146 ("net: stmmac: correct MAC propagation delay")
> Link: https://lore.kernel.org/all/ZMGIuKVP7BEotbrn@hoboy.vegasvil.org/
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> 
> [...]

Here is the summary with links:
  - [net-next] Revert "net: stmmac: correct MAC propagation delay"
    https://git.kernel.org/netdev/net-next/c/81b04a800d3c

You are awesome, thank you!
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